They definitely aren't the best sportsbook out there, but they are one of the best for sure. Hope they keep functioning in this manner for a long period.
Yeah this one does grate with people, but I think it's only because we're used to the permanent levels that early crypto dice sites implemented. End of the day, though, the cashback/rakeback systems (that's really what these loyalty programmes are) are just a way to balance out house edge. Sportsbetting works a little different -- with SB, you get the best value on odds. With the price boosts, and the acca bonuses/insurance, and various other promos always ongoing, this already means you get the most value from sportsbetting at SB. I'm not just saying it either, I bet regularly on sports and it's money on the table almost every time, at every other book. So yeah, you don't get as much cashback from their VIP programme (Clubhouse), but that's because you get them already on every bet (if you choose your odds, use price boosts, apply promos, etc.).
The fact also that once you have been VIP, your account doesn't get the nonsense restrictions on winnings I have experienced at others (even at the highest VIP tier). You bet, you win, you withdraw. No fuss. That's the true basis of why anyone would play at a sportsbook.