Valid point about not-meeting the STR requirement only imposing a movement penalty. I thought it also gave you other penalties but those only apply when you arent proficient with the armor. That said, if you want to reach melee combat moving 10 feet less is a rather big penalty. Specially if your moment isent 30 feet or more. Heck even at 30 feet movement thats one third of your movement gone. Only dwarves ignore this penalty but their movement is already 25 feet, so less then most races and theyre not ideal for a DEX build. They do give overall good bonuses for fighters so theres that
Just so people dont misunderstand me, im not saying a DEX fighter cant (or shouldnt) be done. Its an option if people want to play it thats fine. Im not going to tell people how to play or how not to play. I will however bring up some of the disadvantages to the build as I feel they are often overlooked. For the following section im assuming people dont put any points in STR at character creation at all (thus dumping it) and it beeing 8 with a -1 modifier. You only have so many AS points to spend and having a decent CON is often also needed for a fighter. I often see people dumping STR completly if they go for a DEX build, hence why im taking this stance.
Just to start with, DEX beeing more valuable, (for a Fighter specificly) id contest that. Lets compare what both bring (and dont bring) to the fighter specificly and not to DND as a whole.
Skills:
STR - Athletics (short list)
DEX - Acrobatics, Sleight of hand and Stealth.
So right off the bat, DEX influences 3 skills rather then 1. The 1 skill that STR governs however factors into ALOT. It is used to determine how long you can jump, how well you can climb, how well you can swim, if you can grapple someone, if you can free yourself from a grapple (or the retraint effect in general) etc. A pretty long list.
However for the DEX skills a fighter has no acces to these skills (aside from Acrobatics) to begin with unless you took them via a background or a racial bonus somehow. Some of the more 'shady' backgrounds can add stealth or slight of hand but I dont think any of the PHB backgrounds give both. And they might not fit with your idea of your character for the people who think RP is important. And even then, a rogue or bard can outperform a fighter with identical stats and can more easily gain those skills as well. Rogues also have profeciency with their thief tools which is not to be underrestimated.
Saving throws:
Saving throws need a mention as well in this case. Not that you can choose to have DEX as a proficient saving throw but STR is one you have. Most AOE spells allow a DEX save to avoid damage, but STR saves are more aimed at avoiding negative effects. Spells like entangle, entangling strike or monster related attacks that force a STR test (some allow a DEX check instead but not all). Some monsters (shadows IIRC?) drain STR until you can negate the effect with a spell or a rest and if your STR reaches 0 you are dead. Thats true for every stat btw but relevant here if people dump STR. Sometimes you need to strong arm your way into a situation by lifting, breaking or moving something and DEX cannot always help you in those cases.
DEX also factors into AC and initiative but we both brought that up already. Id say the bonus to AC generally speaking balances out when you are comparing top tiers of both armors. Considering you roll a D20 and add the iniative bonus ontop of that it doesent always matter how high your bonus is.... If the D20 rolls a 1 your very unlikely to go first
Now I do want to bring up another fact that we havent brought up about DEX based fithters. Well kinda, because we have brought up weapons. But specificly their damage die. For melee weapons the highest you would be able to go would be a D8 for a Rapier (unless im missing something?) while STR based weapons go all the way up to D12's. The reverse is true for ranged weapons mind, thrown weapons are max D6 while bows and crossbows can go up to D8's or D10's. That said id say thrown weapons are generally only used as filler when a fighter cant reach combat in 1 turn anyway and he doesent want to throw away his turn or run head first into enemy lines on his own. So the extra range that bows have only matters if its your main source of damage.
And this is ofcourse fine if you were going for a ranged fighter or more of a skirmisher build to begin with but my point (sorry for taking so long to get to it lol) is that it severly pidgeonholes you into a select few weapon groups and the best case scenario for you would be ranged when it comes to damage dealing. Is just doing the max amount of damage the only thing to your character? Ofcourse not. But it can be important for people to take both the advantages and the disadvantages of builds in mind when they are considering one so they dont get a nasty suprise they dident know about later down the line. Sorry im not really concise, not one of my strong sides im afraid
In addition to this:
An interesting way to gear your fighter in BG3 might actually be to go for medium armor instead of light or heavy! Lae'zel comes with half plate right? With DEX14 (at least) that gives you an AC of 17 before factoring in shields and your fighting style. With both thats an AC of 20 at the start of the game! If you just go with the +1 AC fighting style you could run a 2hander (or 2 weapons) and still pack an AC of 18. This would leave her without her armor obviously but if you dont want to take her along anyway or want to kill her that frees up the armor!
