Definitely useful to have queries based on feature existence with overlays (also for pricing! Discount coupons, price overrides... all very useful). All the advice about feature flags and progressive enhancement for the web, totally applicable to billing checks.
One thing I like though: try to make your feature matrix as dirt simple as possible. If you can find the pricing that just aligns with value, you don't have to play "which plans get this feature" _every single time_ cuz you know the pricing is capturing the value.
As a solo dev working on my SaaS, I can second this. My time and attention are scarce, so I ditched my earlier attempts to also have a monthly paying plan, for example. I also don't do coupons and sales. It was tempting to offer these things, but it wasn't grounded in reality. Choosing for the most dirt simple setup saves me a lot of time and it keeps the complexity at bay.
As another solo dev running a SaaS (7 years), I mostly agree. I stopped doing sales and coupons, it's a lot of effort for little practical gain (in a B2B SaaS you really care about the long-term, not hooking customers based on quick promos and coupons).
But complexity will catch up with you eventually. There is just no way around this. I read the article and I agree with most things there — my system is somewhat simpler, but I do have "features" and feature overlays, which let me override entitlements in specific cases. This gets a lot of use. And right now I'm working on plan overlays, so that I can offer custom plans when needed — and believe me, it's not because I have too much time on my hands, it's because I started to really need them.
One thing I like though: try to make your feature matrix as dirt simple as possible. If you can find the pricing that just aligns with value, you don't have to play "which plans get this feature" _every single time_ cuz you know the pricing is capturing the value.