Various models about in the market.
Some allow max of units others not.

Not much of a problem in AB.
There is no additional purpose to maxing the unit.

Skills are fixed.
Elite is a flat % bonus
There is no Elite Adult content or outfits
There is no content that requires Elite tanks

And of course it is 5* tanks where most other games hand out what is their 4* units.
So as far as rewarding goes, AB is more than a little ahead there.

ABs problem remain Art (too vanilla and too little produced) and Content (much expanded basics, but still same basic farm play) and the main challenge is if they can keep events coming.

This is an ok starter.

But they need to use the 3 weeks "break" it gives them (while the event runs) to get going on non-farm events and better adult content. Basically change up some gears. There is only so many times those tanks can walk the path over the screen before it gets stale, at that point either the Waifu drives the player or more interesting content or player burns out.