I think the article was pretty well-informed and sourced analysis. Yes, as you point out, NATO has undertaken offensive campaigns. I think the author made a mistake of saying "alliance" here when they meant to say "treaty".

AFAIK, none of the NATO articles were invoked as part of the operation in Yugoslavia. That is to say, though it was a NATO operation, members were not bound by treaty to participate.

This fact muddles some of the points the author made, but the author speaks broadly of the ramifications of invoking Article 5, so I would say their analysis is well-reasoned.

> NATO's intervention was prompted by Yugoslavia's bloodshed and ethnic cleansing of Albanians

Yes, should've just turned eyes away from genocide in Europe.

So you agree with my point that it's not a purely defensive alliance?

Let’s make an agreement called YCTO - such that I promise if someone attacks you in comments, I will defend you by attacking your aggressor, and if someone attacks me in comments, you’ll do the same.

… that agreement is purely defensive.

If you and I see some vile rhetoric that is directed at someone else, we can both decide to attack it, even though it’s arguable our actions are offensive. That action is independent and not bound by the YCTO.

We just both agree, independent of the YCTO, to act.

It’s a function of like-minded values that made the decision.

Yes. By entering the conflict:

1.a) NATO declared that "defense only" claim is a lie.

1.b) Other countries will now ask themselves what else in NATO charter is a lie.

2. USA, the permanent member of UN Security Council(which is de-facto enforcer of all UN decisions), severely undermined UN authority.