In Runescape, RPG MO, Damascus, Curse of Aros, Eternal Lands, Milky Way Idle, Melvor Idle, New World and pretty much every other "skilling" game in existence has a reason for "skilling".
There needs to be a reason for "skilling" up other than a number going up. Every now and then something needs to open up. Such as a dungeon, bosses, etc... Why do I want to be a level 60 blacksmith/60 combat? Why do I want to be a 100 blacksmith/100 combat?
The reason can't only be a number going up or "maxing". Just look at Brighter Shores for proof. Brighter Shores was dead on arrival because there is no reason to skill up. No bosses, no goals, just a number going up. There needs to be well thought out carrots on sticks throughout the progression of all the skills. Reasons for the mid game, end game, etc...
My 2cents!