I wouldn't say raiding in TBC was a niche activity. Higher level was certainly done by a smaller percentage of the player base, but raiding in general even just Karazhan was pretty popular.
Nah. Remember back then you couldn't raid cross realm and had no dungeon browser. Just because trade chat was spammed all day long for Karazhan groups doesn't mean more than 10% of players actually raided.
Is it time for a "if you don't like it make your own group" reply? I think it is, because it always is!
and it still wouldn't be wrong. If you're going to have a character that's behind the curve compared to everyone else that's applying you are going to need ways around that.
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Tier itself isn't a mistake. It just doesn't work well with Titanforging because of how powerful most tier bonuses are preventing you from using your TF gear even if it's 15-20 ilvls higher with ideal stats. Since TF is going to say, Tier has to leave in order for the game to remain rewarding.
Dungeon is still going to be inferior to mythic raiding since Azerite gear and weapons can't TF.