Why do Japanese romcom authors love adding this annoying lesbian in their works. My god. You are not cooking with this one, author.
I presume they do it because people ultimately respond to it positively enough, in net-- despite any complaints.
How much do people complain about the antics in Rent-a-Girlfriend, only for it to have over 400 chapters, volume box-set options, at least four seasons of anime adaptation, AND a live-action adaptation?
This is less egregious in comparison. We're almost certainly still going to be back here next chapter. The people that like it, like it, and the people that don't are probably not dropping the work as long as this new character doesn't usurp the ML's position-- it has to get that bad.