Power creep is something just about every game faces through it's life. Players want new toys to play with and, especially for RPGs, they want to feel like they are growing their character. However it leads into the problem of power creep that is only going to get worse and worse the longer we ignore it. Level syncing is a good start to help make sure the old content isn't obsolete. But with every new expansion we are still scaling in power beyond what is sustainable.
SE just did a stat squish to curb power creep. Numbers were getting too high. And yet despite acknowledging the issue they still introduce more potency buffs and spells and traits that are only in effect for certain parts of the game. Scholar has it the worst. It has Ruin and then 4 different versions of Broil. Explain to me what it is about level 64 specifically that magically turns a potency of 165 from balanced to completely underpowered. Why is it that jobs like GNB can have the same basic rotation from level 26 though the rest of the game? The whole point of potency was to create a generic multiplier that you only had to set once and it was effective at any level.
Why is it necessary that every expansion be another doubling of player power? Surely it can't be for the sake of players want to see bigger numbers, because we just squished all the big numbers. I'm not saying don't make your character stronger as you level, but if all we're doing is making numbers go bigger you get that same effect already just from improving your gear.
On top of it being unnecessary it makes balancing jobs a complete nightmare. You have to spread an entire job's toolkit across more and more levels. This leads to some jobs being awful to play for certain ranges while they wait for their basic skills. Every time a job gets reworked they have to be retroactively reworked for each expansion as well, just so old content doesn't break. And it means limiting the amount of content where we're allowed to use our cool new abilities since the new stuff is always made absurdly strong. Why can't our power increase just be linear so we don't have to worry about these issues.