Thank you for your question which gives me the chance to clarify some things.
The link you are referring to is not talking about Indo-Europeans but rather about Aryans. My apologies for triggering that confusion, but sometimes you have in your mind some things which sound very different for other people (for me Aryans and Indo-Europeans is the same thing, and both were inexistent). I should have left the "Aryan" part out to avoid confusion, so again I apologize.
That Aryan theory was obviously "discontinued" because it was considered not to be politically correct (see Nazi). But make no mistake, Indo-Europeans are considered a race (or ethic group, or people, whatever they may be called by each person) and scientists are trying to track them by their genetic signature. They have talked about invasions, about how Indo-Europeans tamed the horse which gave them a tactical advantage, etc. This is, after all, why renowned scientists, like Colin Renfrew (whose I am a huge fan), keep pointing out that it is wrong to talk of Indo-Europeans, but rather of Indo-European languages.
Lately, they have been saying that the Proto-Indo-Europeans (the ancestors of the Indo-European) were a hypothetical prehistoric population. Despite of talking about Proto-Indo-Europeans, placing the word "hypothetical" is something I guess...
The Indo-European theory keeps changing. Wikipedia pages even faster. But if I ever read on Wikipedia that there were no Indo-Europeans, trust me, I will open a bottle of champagne!
Edited 1 time(s). Last edit at 12-Aug-21 08:01 by Angelis.