At least Dusk Vigil and Sirensong Sea needs it along with whatever else is the first dungeon after a new expac because of the high ilvl variance for lvl50, 60 and eventually 70.

The other ways to level like PoTD or synced roulettes and now alliance raids that don't need much gear or it is synced down is making the problem worse because you can just level to 70 doing those in your low level gear and not touch SB leveling dungeons so when you actually decide to go do one or get it for leveling roulette by chance your gear might end up incredibly bad.

It is somewhat a problem with the way the game is set up. The quests are one time per character. In other games they don't usually have this problem due to either scaling gear or because every time you make a new character you can do the quests again. If you play another job on the same character on XIV you might not have the gear feeding quests anymore and you can level doing super old content and bypass the new leveling content.

Sure you can go to MB and buy some gear, grind poetics to get gear (I wouldn't even do this tbh, seems like a waste of time for gear that is rapidly replaced), or buy from an npc but players will usually take the easy way out. Some players don't care if you are incredibly gimp if this forum is anything to go by so they probably end up not caring because in most cases no one bothers to say anything unless it is causing wipes.