Tokio is 1.0 since 2020 and they declared to maintain backwards compatibility for a minimum of 5 years. Tokio already made backwards compatibility guarantees and it hasn't been killed so far.
For example, Tokio has the concept of "unstable" features, which have stronger stability guarantees than Rust nightly. First, you can use them with the stable rust compiler, second we guarantee that unstable features will not break across patch releases. This may seem small, but it lets us experiment with new functionality and get real world usage. Many of our users cannot use Rust nightly but can use Tokio unstable features.
I didn't imply anything about Tokio. I just wish some libs didn't need to be bikeshedded (like async runtime, time, decimal, etc.)