It would be overpowered because some feats give a stat increase besides their feat effect...
You're just saying what it does. Not why it would be overpowered. Then you say it should be clear why it would be overpowered.
Let m give you an example:
Shield Dwarves get +2 CON, free armor proficiency with medium armor, free weapon proficiencies, Darkvision and a few minor boni (not entirely sure whether they get all of it in BG3).
And on top of all of that you want to give them a free feat at level 1.
Now consider what you can do with feats and tell me again it's not overpowered without a price to pay for it.
