To be honest, the science behind it is really complicated and requires a lot of knowledge of human biology.
in a nutshell, what you said is right, but you start to get into things like fast twitch muscle fibers versus slow twitch and things like that.
it also depends on what kind of riding you do. Long distance riders probably will see little benefit from weight training in their cycling, as weights use fast twitch fibers and slow cycling uses almost always slow twitch.
criterium racers benefit a huge amount from weight training because they frequently have To recruit fast twitch fibers in the frequent, all out, short sprints that occur in criteriums. Road racers are somewhere in the middle.
the rule of thumb is, the shorter, more intense the effort, the more weight training will benefit.
keep in mind though, weight training overall is good. The pro racers you see in the tour de France are, in many ways, unhealthy people. Their training is so focused on the singular goal of propelling a bicycle forward that many parts of their bodies not needed for that go untrained, and they get so skinny that a cold can lay them out for weeks.