This isn't really a debatable topic. If you want to ignore someone, ignore them. If you don't think it's right, then don't. There is no rule, either way, that must be followed.
We're all on this site for different reasons. Some people enjoy debating with others, or at least with people they perceive as false teachers or general nuisances.
Others would rather avoid the drama and frustration.
Neither is right or wrong. Go by your personal conviction.
We're all at different places in our walks and growth. Some may struggle with patience more than others and ignoring people may help that.
It may also help some people to ignore certain others to keep themselves in check. I know I've seen people on here that just irked me and I either go to war with them, or put them on ignore. So I choose to ignore them rather than possibly get banned.
In my early years on this site I did create a lot of drama, myself. I'm sure I ended up on plenty of people's ignore lists. It didn't bother me then, nor would it bother me now.
If you're content with your subjective opinion, problem solved. It is not an important issue worth debating over.