Most uptime checks answer a narrow question: did the homepage return a successful response?
That is useful, but it is not the same as knowing whether your product works.
For a small SaaS, the more important question is:
Can a new user discover the product, sign up, and reach the first useful screen right now?
A homepage can be green while signup is broken. Login can fail while the marketing site looks perfect. A background job can stop sending onboarding emails while every public page still returns 200.
