I have gotten this achievement in december 2020, so it's still possible. But you will need an open NAT.
There are plenty of guides on the internet that will tell you that you need to open ports x, y, z etc...
Personally, I got an open NAT just by forwarding (opening) the ports 27015 udp to 27015, and the port 3074 udp to also 3074.
Oh, and also, don't forget to raise ping limit to the max in search options (S key).
It helped a lot to find games.
Sometimes there are also just not enough players, so you're going to need to try at a different time.