I understand that, that's the purpose of this metric, the uptime with respect to requested number of workers. This really useful.
If someone doesn't get all the workers they request OR if they're having particular workers failing, the computed topology uptime will go below 100% which is what you want. If you strictly just count the number of workers right now, you'll get uptime of 100% even when workers are dying. I think what you're hinting at is you could look at the scheduler to see situations like with the even scheduler where the scheduler chooses to allocate less workers then requested and this could be considered 100% uptime, I don't count that as 100% uptime and it's incredibly cumbersome to get the number from the scheduler.