Except that's not how legal cases work.
Just because all three of you infringe doesn't mean lawsuits will result for all three.
It's quite likely they would allow Youtube and Netflix to continue infringing to promote the growth and adoption of the codec whilst they go after smaller players who won't be able to put up a fight.
This is why grassroots-scale efforts to defend against patent trolls are so important - you absolutely have to prevent precedence case building for patent trolls or it becomes so much harder down the road.
You can try and invalidate the patent but in a situation like this where the patent holders are serious companies and legitimate innovators it's unlikely to get you far.
And yes it is very common to bully lots of smaller players rather than get into an expensive protracted lawsuit with a large one.
I am not aware of this being the case for either company.
In a lot of jurisdictions a 3rd party can join a lawsuit, it's called an intervention [1].
I'm not fully aware on US law, but e.g. in NL all large internet providers joined a lawsuit as defendants when a copyright enforcer wanted 1 to block The Pirate Bay.