I don't believe it is true. They might block commercial solutions, but i'm using Wiregiard with exit point in Netherlands right now, works fine (although on certain providers, I've seen some throttling, but that could just be coincidental)

UPD: I asked some friends, some of them have faced probmes. I guess it is not protocol block, but instead combination of protocol and "suspicious" server. Mine has stuff other then VPN running on it, so it might have flown under the radar.