Don't you think just replying with "ok" is extremely rude?

Just recently I noticed that some people say "ok" when someone is saying something they're not interested in... for example, one of my teachers just said "okay" anytime another teacher or student would talk about themselves. Like they'd give a little story and then she'd just smile and say "oh okay." Like come on you can think of something better to say right?
I have two friends who just picked this up. I was texting one about how I was annoyed about something and she just said "Okayyyy" like wtf?
And I just sent a text to another friend telling her about something I saw on TV and she just said "lmao ok." Seriously if you're completely uninterested just say something else. Its not hard to be polite. I just think this is the rudest thing that people apparently do very often.
Anyone do it? Or hate it?
Updates
+1 y
I have to listen to boring shit from people I'm not interested in too I just think of better things to say than "ok"
Don't you think just replying with "ok" is extremely rude?
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