This option is a waste of time.

Yes, it's possible for a newcomer to not know the fight and screw up.
But even with this option it's still possible for a carried-clearer to enter and screw up your fight anyway (and they are more prevalent, if you've ever done these fights before.)

The amount of anguish this option would solve is insignificant.

The solution to this problem (grouping with unknowns without knowing their skill level), is for the starter of the PF to form a static.

That's what statics are for.

This option is not what PF is for.

Yes, you are allowed to have a goal of clearing content with similarly skilled people and ignore everyone else on the server.

But the only reasonable path to that goal is a static. Every other suggestion like this does not make that path easier, it makes it harder (you're meeting less new people who could be a great addition to your static).

It's a waste of development time.