Also from a user perspective there are many benefits with a software that exists on many platforms. It's often better with a slightly less good/snappy app that runs on all platforms than a perfect app than runs only on one platform. It's a feature.

It could also be said that it's a feature that the app does not 100% follow the native UI as the experience will be the same irrespective of which OS you are on.

So you sell everything as a feature?

Is it a feature, that MS Teams (as a default setting) does not use native notifications on OS X? As a user, I have to disable two notifications now, because one does ignore the system setting. I don't know how to sell that "feature"... Imagine having many apps with each having it's own notification setting, layout and appereance.. That's hardly an improvement to the status quo.

I don't use teams, but MacOS notifications are mediocre at best. I would consider a better implementation by app a feature.

Sure but the parent didn’t say better. Is there any example of a better implementation since Growl?

That is only a feature for app developers and (especially) the marketing departments of companies who do so, not platform users. I use non-platform native UI as a leading indicator of contempt for users.