As someone who has played D&D for 40 yrs, I have to agree with what the others are telling you.
Although you are more than welcome to play whatever you wish, in whatever fashion you wish, a STR based Monk using Standard Array Ability Scores or point buy (the systems BG3 is using) is at a severe disadvantage. Same with wearing armor as a monk.
You get more bang for your buck by maximizing DEX (affects to hit bonus, damage bonus, most common save, most commonly used combat and combat adjacent skills, and AC).
By wearing armor, it is like walking away leaving free money left behind on the table. By wearing armor you are giving up a class benefit of unarmored defense, while not really gaining anything in return. Wearing armor heavy enough to get a higher AC than unarmored defense of a DEX monk, means gaining disadvantage on stealth, etc.
If you want an armored fighter that fights with their fists, play a fighter and take Tavern Brawler - but a dex based monk is still better. It's like putting a trailer hitch onto a ferrari and trying to pull a 30' trailer. Can you? Yes, but why would you? If you want to pull a heavy load buy a truck, a ferrari isn't made for it. Again, can you... yes, but you're not playing to your strengths.
As a monk you want to maximize DEX, then put your next 2 highest scores into WIS and CON. This not only helps your AC, but also helps with HP (if you are going to be in melee range, you need to be able to take a hit, and as others have pointed out, the game likes to pick on low AC and low HP characters first).
Patient Defense + DEX build makes you very hard to hit, gives you excellent damage output, good skill check scores, a good dex save. It plays to your strengths.
There's nothing wrong with a STR build monk, as long as you are doing a manual roll for ability scores (and get lucky with a lot of high rolls), but with standard array or point buy system means you need to prioritize 3 scores... DEX, then WIS and CON. You can roleplay it anyway you want, but those three scores are a must.
