Steam workshop gives you less mod control.
It is a nice easy button but honestly the BG3 mod manager is just download, drop in, drag over, and adjust the order if you need to.
Well, I don't give a shit.
I still prefer a comfortable one-click install and automatic auto-updates.
I already dealt with the BG3 mod manager and with the Nexus client in EA. I would gladly do without both if I can help it.