Well, no, because after you introduce you gotta DO something with ‘em as they are precursors to the Mane 6. Writing them out is not the solution, limiting their screentime would’ve made it worse (Doesn’t help this group includes someone foreshadowed since season 2)
Look at Cadance and Shining - Twilight leaves the pair to guard Flurry, even though those two fighting Chrysalis would’ve been fascinating. Shining is doing what a guard can do, while his sister is risking her life. Starlight at least had a go at tussling with Chrysalis, though ofc, she mostly just used teleportation and blasting. Just missed potential all around to rehash plot points from previous finales, because they got too many powerful magic users that need to be nerfed or written out. It was a problem with the Princesses, it was a massive problem with Mr. I Can Do Anything Discord, and the Pillars got the same treatment.
IMO Tirek is not nearly powerful enough to have wasted them so easily. Twilight says “and they’re more powerful than ever” And the problem is…Chrysalis, and Cozy are….Tirek was literally a god at one point, the bell restored him to what appears to be his default.
And I never said last episode has to be a battle - it can be second to last. And allies showing up and fighting for Equestria would only strengthen the message rather than the “Mane 6 are always the solution, and we’d be screwed without them”, heck, it can even be the thing that powers Twilight’s rainbow laser.
And it is not like the epilogue was even set entirely in the future, so a scene or two of exposition and the closing song montage would’ve more than enough to show where are they now.
The finale disappoints, not because there isn’t things I like - but because it is the finale and they played it PAINFULLY safe.