Funny, I'm not with OVH but much cheaper hosts. I have had multiple DDoS attacks on 2 of those servers so far (both with different hosts) and the only way I noticed was their notification system sending me a message that they suspect an attack going on and asking me to report why this may be the case. I do have an application, with a few thousand people using it, running on my server, so yes I do notice any downtime especially since I have a monitoring system running.
It might be true that OVH has a great setup to prevent attacks. But just because they do, does not mean that cheaper options do not.
So no, OVH is not the only option and OVH is certainly not "the best" because of one single feature. People are way too obsessed with DDoS.
It's possible the attack was not large enough for you to notice. It's impossible to tell with one anecdotal response. When it comes to game hosting there's only one real choice, OVH.
Everyone is obsessed with DDoS attacks, because it's the one thing out of server owners control, and it's infuriating. One pissed off team or other server owners will consistently take your server offline for their own gains. DDoS protection is especially needed for launch, as that's when the competition hits. Teams will hit you if they are losing wars. Random people will try to blackmail you to give them stuff or they'll keep taking you offline.
It's not just whether an attack happens, it's how big of an attack it is. OVH is the only host that's proven to be nearly impossible to take down. Aside from exploits getting around their protection (long patched) or actors in their own networks attacking from within (no longer a threat due to detection methods put it place the last few years).
Bottom line, if you're hosting a long time game server, DDoS protection is the most important factor. (and uptime)
There's a reason why they're the most popular on my server list, they're reliable.