3 had potential to be something really good but was boring and repetitive as fuck to play, I think I killed the first mob boss then was nah I’m cool 
The story concept was good, but the game, even beyond the repetitive gameplay, was fundamentally wrong.
Mafia was good because of the grounded tone and restricted gameplay style, turning it into another GTA close was idiocy.
In Mafia 1 you had the get gas, couldn't go over the speed limit, and so on.
RDR2 felt more "Mafia", in that sense, than Mafia 3.
And even the activities, Mafia was a linear game set in a large, unified map, it was never supposed to have side shit and "stuff to do", in 3 they straight up put that side shit as the stuff you MUST do.

Mafia 2 got that a bit more, but its story was so uninspired and botched (in the second half) that it didn't really matter.