If you just want random games you can use TF2Center. Actual competitive is organized through UGC or ETF2L or RGL or whatever else. PUGChamp used to be an option but I havent used it in awhile and don't know how its doing. And then there were altsites like HLPugs, tf2pickup and so on. A lot of options, and yeah Valve Comp is still there so maybe while playing casual just queue in and see what happens