I believe that’s pretty much what happened after the dot-com crash. A lot of fiber was laid during the bubble, it went dormant after the crash, but it was useful afterward as the internet continued growing.

Automatics also allow for engine braking. From a quick search, it sounds like a toss-up as to whether that triggers brake lights. Regardless, the article mentions the benefit is not only from cars slowing down, but also from indicating that a car is preparing to stop or “that a stationary vehicle might initiate movement”. Neither of those can be done by an engine brake, so front brake lights would still have a benefit even with a driver that likes engine braking.