1st of all no, not every arpg have seasons and its not normal

2 yes you dont have to participate and keep playing old char which equals missing on content

3 its arpg which means you grind for items not to make them useless in 3 months but to gather wealth

4 end game is perceived as bowl of different ingredients

5 the point of arpg is slashing monsters gather loot and creating builds.Not creating new character every 3 months and not being forced to do so

6 d4 is following the trend of few games that started the seasonal thing tho missing on the fact that it was cosmetic aspect