I think a part of it is Tactical Adventures had nothing so why not use the rules that WotC gave them where Larian had all this stuff already working so fell into the temptation of using what they already had and tweak it to fit 5e. BG3 is prettier but SCotM feels more like a true tabletop 5e experience.

It will be interesting to see if Larian will be willing to embrace the 5e rules to make BG3 a better game though that would be a huge amount of work for them.

I really hope SCotM is successful and would love to see what Tactical Adventures could do if they had Larian's resources.

I plan to play both games, 2021 looking to be a good year.