In general, there is a 5e problem where classes that rely on subclasses for tier-defining features have issues.
Level 1/5/11/17 is, in my opinion, an important level; they open up a new tier.
Level 1 you need to get enough to differentiate you from other starting adventurers, yet also not so much that a 1 level dip is crazy good.
On the two ends of the spectrum are Fighter and a full caster:
5 competes with extra attack/3rd level spells.
11 competes with extra attack(2)/6th level spells.
17 competes with action surge(2)/9th level spells
Classes that rely on subclasses for their tier-defining stuff end up with a problem, in that balance control isn't going to be as good on subclasses. On the other hand, there are classes like the Barbarian whose main class features are hot garbage, so blaming it on subclass specific issues is maybe wrong.
With subclasses, you'll get lots of variation within each one.