They hold a monopoly of merit, many tried EUV and they succeeded in doing something that others were calling impossible even 5 years before they shipped it, not by shutting down competition but simply because no one else could.

The idea that ASML would somehow be more worthy of merit if Nikon/Canon also succeeded is weird.

Would the moon landing me more impressive if Russia and Japan also managed it?

Exactly correct. They're literally more deserving of credit because they've done something that to this day nobody else has been able to do.