Why were portal 2/cs:go removed from the Beta?

Okay I know I’m late and this is probably a shit post, but I remember in the gmod 13 beta there was support for portal 2 and CS:GO models. What happened? They worked fine for me, even if the maps didn’t work, the models were fine.

It’s a problem with Steam Pipe, or so I’ve heard.

What About Left 4 Dead 2? That worked fine in Gmod 12.

Only because the survivor models were partially invisible in lod0.