I think it is also a matter of character concept and backstory not meeting well with mechanics. I think that some of the iconic characters for pathfinder materials fall into this trap (some not all).
You have these level 1 PC class characters with backstories of them completing or accomplishing things that would be hard by even the standards of a level 3 or 4 character (sometimes higher). Then all of a sudden they start actually getting played and they are a joke compared to what they have done in their back story.
Realistically, whenever a player comes up with a character concept they should be thinking that this person was a adept/commoner/warrior 1 before achieving their PC class lvl 1. What they could and couldn't do was basic at best. Grand accomplishments from the past should be framed more as oddities of fate or luck and not so much as character skill and ability. Any level 1 character is probably within the first year of achieving their first level in a PC class.
Its also a matter of player expectation. A lot of players I know basically want medium difficulty enemies that are bags of hit points and not anything that is an actual challenge or threat. I have seen a lot of people get upset because they felt like their character was not overly effective in a large number of encounters or even in "boss fights". This also has to do with how a character defines "effective". I've seen players dish out heal, battlefield control, party boosts, and hinder with status effects all in one combat but b$!$& that they are not effective because their ide of effective is basically damage related. I'm not immune to wanting to feel like a badass and be an unstoppable force but I try to check myself and stay in the game.
I mean most adventures never make it to hero status and end up dying long the way. Even then, what qualifies as "this should be challenging" vs "this should be a cake walk". My group just finished up Strange Aeons, the last fight was difficult and we felt like we might lose for a lot of the combat (we didn't) but stepping outside my head and the fact that I wanted a guaranteed win, allowed me to enjoy the fight for the epic nonsense that it was and the real fact that if we lost the end of the world would have happened.....which would have been a good story in its own right.