On the larger C's, 29-32' I can see where a lot of folks feel the need for levelers. On the smaller C's 19 - 25', not so much. On our 24 footer it is just too easy to simply place one or two Leggo blocks under one side or the other. Yes you need to block both the duals when lifting one side and I have never needed to go more than more than two blocks high. Simply pushing a button is easy but often you need to get down on your hands and knees to make sure they are properly/securely set anyway.
Salesmen love to push levelers. They are a very high markup/profit/commission item. The irony of folks spending 3 to $4K+ on a set of levelers is that they don't always work. Leveling systems are often problematic at best and like slides, sooner or later they will give you trouble. Walk through any campground and check the rigs with levelers. I'll bet you find at least half that have blocks under the levelers. Given the ridiculous cost, the added weight that comes right out of your payload and the simplicity of just putting down a couple of blocks I really just don't see the need.
As always.... Opinions and YMMV.
:C