While I agree that Stripe is great for payments, Stripe Subscriptions and Stripe Billing were never really built specifically for SaaS. The problem seems easy at first when you have just one plan at $100/month, you'll quickly have many more plans, all kind of discounts and special deals, custom "enterprise" plans for your larger customers and design partners, while having to grandfather your existing customer base and also allow easy upgrades/downgrades etc. A lot of SaaS pricing these days is built around tiers with certain usage limits on individual features, so you'll need to built that as well. And if you are working on an application with a fixed underlying cost for certain features (like genai tokens), you'll also have to implement metering. None of this is really part of your core product and yet most SaaS startups spent a lot of time building and maintaining (billing is hard!) the same functionality over and over again.

There are a few new modern players (disclaimer - I'm the CTO of one of them [0]) in the SaaS subscription mamagement and adjacent usage billing space now and I would highly recommend using such a solution while still relying on Stripe for just the payment processing part. It will save you a lot of technical headaches down the road and even should allow you to get started quicker (for example, we provide you with embedded pricing pages, quoting and sign up links, feature entitlements per customer, full metering support and much more out of the box) and iterate over your pricing faster as you grow.

[0] https://wingback.com