[vamos_davai]

Their platform, their voice. It's not part of public domain. Unreasonable outrage from the HN crowd.

[robdachshund]

Just because you can do something does not make acceptable to all people.

What you are talking about is essentially moral relativism. Most people see that as dubious.

Just because one entity sees something as right does not make it objectively right.

Can Instagram do this? Yes. Should everyone be okay with it in virtue of that ability? That comes down to personal opinion.