Honestly what do you consider wrong with those two titles? The fact that they aren't single player games, or that they aren't graphical powerhouses for the PC? And what would you want him to be playing instead? I say this as a (damn near) 42 year old parent, and I don't see anything wrong with him playing either of those games. My kids all play Minecraft and a couple play Fortnite and Overwatch, and my oldest used to play a lot of Rocket League. While I do wish they had more interest in the games I grew up with (and there are a few I can get them to play) these are the games they have interest in, and there is nothing wrong with that.
As much as I loved me some good old single player games, once I discovered online games I was hooked. Coming into PC gaming at around 1997 (my bud had a PC, I didn't get one of my own until around 2002) and when we discovered Worms 2 online I was hooked. Nothing was cooler at the time than playing someone all the way across the world in Europe, and just talking with them as we played was mind blowing.
If your kid was playing some mobile whale hunting trash I would definitely be on board with you, as I find those games are absolute garbage and deserve every bit of shit they get. But your son is likely playing those games because they are fun for him, and more importantly his friends are playing them and it's something they can do together. I did the same thing with my buddies at his age, the only difference is it was mostly local co-op with friends on a console, but that did transition to online as that world started to open up for everyone. My oldest has gotten more and more into single player games as he has gotten older, but he will always drop them to play with buddies, and I can't blame him a bit for it.