Lack of End Game Content

[linay]

That is correct. Now apply the modifier "endgame" to content and you get "max level things that are included in something". The reward you get is the max level content, farming that reward is the max level activity, running Sastasha doesn't fit the definition of "max level things that are included in FFXIV" and so that is not endgame content.

The reward you get is not the whole max level content. It is also the activity associated with getting that reward.

If someone asks you what is there to do at max level, you can tell them to do raid to get raid gear or to do roulettes (or other means) to get max level tomestones for tomestone gear which can be further upgraded. Those are alternative endgame content for people to do at max level in terms of gear progression.