That last part is propably true, but i disagree with the things you said before, might be, that it's just a sample size thing, but i've got a friend with the same config as me, crappy b450 board, but he got himself some rgb ram, becuase he liked how it looked, it was some crosair kit with 3600 16-18-18-38 which he got to 16-16-16-36 easily, while repairing a pc for someone else i also had to check some 3600 sticks (dont remember timings), because the pc was having ram related boot issues, which happaned to turn out to be a damaged dimm slot, and they worked fine with my config. From what i´ve heard of from others without having experienced first hand, that almost all go to 3600, with timings very much dependant on the kit that they have and that a large ammount also go to 3733. Like i said, propably just luck within the sample size.
I think i'll take your word tho, while i've built pc's for a long time, im pretty new to overlcocking, and i'll just get a better cpu first.