An MC being a beta isn't the only problem of the harem novel. If anything the problem is less with the MC and more with the harem members.
I see things this way, romance is the hardest thing to write as an author. And harem multiplies that difficulty for every harem member. Most web novels are incapable of writing harem and even the good stuff are generally harmed by harem being there.
The Second coming of avarice isn't too bad and the author can write quite decently considering its slow pace. Probably due to experience in writing MEMORIZE. That said, the fact that the MC is the most sexiest thing alive and the fact that he wouldn't have made it out of any arc without his harem is an off put, but other than that.
EER is also a decent read like many of Toy cars works, and like many of his works the harem does drag the whole thing down. That isn't saying it isn't worth reading, just the harem aspect is the worst part of it.
Since the harem doesn't drive most of the story its less of an issue until towards the end.