What is the deal with some heroes becoming more niche than ever?

With the introduction of armor especially spell and physical version some heroes are more niche than before. Anubarak has its health reduce in order to make his spell armor not too strong, but when that happens his aa resistance is also indirectly nerfed. Balanced, but has become niche. Given quickmatch is a thing and people get to pick whoever they want to play plus how the team comp there is basically a mess right now, I don't see the need for heroes to be more niche. Play unranked draft, or ranked yeah but that is not my point. This game was not designed with competitive as a priority, but more of fun. Unranked Draft is not entirely for the fun even if it is unranked. By doing this it merely become a game of rolling a dice even more than ever before. And in even/fair matchup mechanical skill will not get you far too because your opponent are equally versed in it too so a messy comp is obviously not going to help and is the sole deciding factor between losing and winning.