Why "habrAzhiteli", "habrAlyudi", "habrAeffect"?

Question

IT terminology

Indeed, according to the rules, the connecting vowel is "O".

Answer 1

What, have people already appeared who do not remember the original domain of the site? habr a habr.ru
Hence these words with the letter a.
And grammar has nothing to do with it.
I will add. In speech, the name of the site was often abbreviated to "habr" - in habr, from habr, etc. In this context, "hacker" is quite the correct spelling.

Answer 2

Here, KMK, the letter followed the speech. For a Russian, this is not the norm, but when a large number of uses are reached, philologists agree to a new spelling.