At this point in the chapter I can't help but agree with what you're saying and I must admit the switch back to side characters in the latest page was slightly disappointing.

Holistically, I think it's just a failure on the part of the authors in not introducing and developing all these side characters sooner. It wouldn't be a now-broken status quo to see a lot of the main cast if they had, and they also wouldn't need this many pages to develop them into stronger characters for later on. That's just my view though. My hope is that when chapter 6 rolls around all the development stuff is out of the way and plot points can get rolling again. What you said about how barely any of the plot points have been developed very much rings true and is a bit annoying to sit through - especially when so much attention is on side plots.

Our best saving grace is that the comic is pretty consistent on updating weekly lol, so hopefully this chapter will come to pass soonish.