That's because the performance gap between different players for that time period appears to have been quite small, so people did not care as much in those days. The encounter design in those days appear to have reflected this as well. Did hard enrages even exist in ARR either? I started playing at the beginning of HW, so I'm not sure. Parsers probably only exploded in popularity among the raiding scene precisely because of how absurdly strict the DPS checks in the Gordias tier was. Actually, a lot of things that caused problems in the raiding scene and the devs' responses to said problems can be traced back to that complete train wreck of a raid tier. (Necessitating the creation of the cross world party finder, for one.)
From what I've observed (and this may not be accurate due to skill changes since then), high DPS in level 50 content was considered to be around the 400-600 range with high end ilvl gear, and most people averaged 200-400. Meanwhile, in Stormblood, you see people with a massive range anywhere between 2k-7k+. The higher the stat/damage gap becomes between players, the harder it is for developers to properly balance new content, especially content tailored towards high-end players.