I'm sorry, but what you're implying is that these companies have sub-par products that unscrupulous writers have been willing to treat as well-made in exchange for cash payment. As someone who (very happily) uses both Backblaze and Squarespace I can safely say this is not the case, and that they're not just "buying their way into" bloggers' good graces.

I'm pretty sure that if they're in anyone else's good graces, it's because they provide a great product with solid service at a decent price. It's absolutely not because they had to bribe people to overlook the fact that they weren't really any good.

In essence, DF is an endorsement-based model. This is one where a justifiably trusted source uses their hard-won credibility to promote products that reinforce their credibility. It's pretty much the opposite of a model that allows people to "buy their way in". Indeed, that's the whole point. You can't buy your way in. If you don't have a decent product, you're not getting listed.