As someone who wrote a lot of code not in the standard library, I championed this RFC pretty heavily. Part of the reason is that I noticed that with the lifetime elision rules, code using abstractions (as opposed to the implementation of abstractions) tends to use even fewer lifetime annotations.
Incidentally, the 87% number is a bit misleading. Before the Lifetime Elision RFC, a limited kind of elision was already allowed (when a function borrowed a value but didn't return a borrowed value). The 87% number was the number of lifetime annotations that were still required even with that limited rule that could be removed with the new rule. When taking all kinds of elision into consideration, the number in the standard library is closer to 95%. (many of the remaining cases in the standard library involve the implementation of collections)
In practice, that means that the vast, vast majority of borrowed references don't require explicit lifetime annotations, and that is pretty close to 100% in "application" code built on top of abstractions.
Incidentally, the 87% number is a bit misleading. Before the Lifetime Elision RFC, a limited kind of elision was already allowed (when a function borrowed a value but didn't return a borrowed value). The 87% number was the number of lifetime annotations that were still required even with that limited rule that could be removed with the new rule. When taking all kinds of elision into consideration, the number in the standard library is closer to 95%. (many of the remaining cases in the standard library involve the implementation of collections)
In practice, that means that the vast, vast majority of borrowed references don't require explicit lifetime annotations, and that is pretty close to 100% in "application" code built on top of abstractions.