Just going to post the same thing I posted on that other thread which is about the same thing...
People are very confused about what things are actually rules changes, and which things are already optional rules in 5e, or standard DM prerogative as granted in the 5e books.
Changing Fire Bolt is a rules change. Changing Hide, Shove, and Disengage to bonus actions is a rules change. Allowing Wizards to scribe Cleric spells is a rules change. And there are several rules changes in the game, and I think it's valid for people to criticize those if they want the game to adhere more closely to RAW 5e.
But many of the complaints are NOT rules changes. They fall within the realm of normal, intended DM prerogative. Facing is already an optional rule in the DMG (pg. 252), and it awards advantage to attackers from behind. (And before you complain about an optional rule, stop and remember that FEATS are also an optional rule in 5e, and nobody is complaining about those.) Granting advantage and disadvantage for any circumstances that the DM thinks are appropriate is already a power given to DMs. "Characters often gain advantage or disadvantage through the use of special abilities, actions, spells, or other features of their classes or backgrounds. In other cases, you decide whether a circumstance influences a roll in one direction or another, and you grant advantage or impose disadvantage as a result. Consider granting advantage when circumstances not related to a creature's inherent capabilities provide it with an edge, or some aspect of the environment contributes to the character's chance of success." (pg. 239 DMG) Higher ground advantage isn't a rules change. It's the DM doing exactly what the DMG says they should.
Changes to monster stats? Not a rules change. Stat blocks are not rules. Every experienced DM I know changes monster stats, makes up new monsters, adds NPC levels to monsters, or adds abilities to monsters, frequently. For at least the last three editions of D&D, including 5e, signficant space in the DMG has been devoted to just this topic. "Part of the D&D experience is the simple joy of creating new monsters and customizing existing ones, if for no other reason than to surprise and delight your players with something they've never faced before." "A stat block in the Monster Manual might make a good starting point for your monster." (pg. 273 DMG) Monster stat blocks are a quick, ready-to-play convenience feature for DMs. They're good for when you're short on time, or lazy, or uncreative, or as a starting point for creating your own unique content. Even in official published adventures, it is very common to see modified versions of creatures, especially changes to a monster's AC or HP.
Also, monsters have a RANGE of hit points. The exact number listed is just the numerical average, again to save time. Complaining about goblins with 13 HP instead of 7 is ridiculous, as even the standard goblin has 2d6 HP base, and full rules exist for making custom NPCs with the race "goblin" and for adding class levels to an existing goblin. As a DM of 30+ years, I virtually always modify creatures in my games from their stock Monster Manual "starting point" stat block. So does Chris Perkins, so does Jerry Holkins, so does Matt Mercer, and on and on. It's not a rules change, it's DM prerogative.
Numerous other things fall into this category, I don't feel like going through the full list of "this is not D&D!" complaints right now. But probably at least half of those issues are not actual rules changes, they're just DM prerogative. Which means that you could dislike how Larian is as a DM, but you have much less ground to stand on when it comes to claiming that the game is some wild divergence from 5e rules. Yes, there are clear rules changes, but honestly not very many of them.
