I’m sorry, but I just get frustrated by the persistant view on this forum (maybe not by the OP, who just happened to encounter my views at the worng time!) that people cannot improve by riding on Zwift, it is just a game, cheating is rife and all those that are serious about getting faster use TrainerRoad.
There are countless threads about it. In all honesty, I’ve probably encountered more people serious about riding on Zwift than I have here. There are all manner of pro-riders that use it as a training tool. Some such as Cav and Thomas De Gent have even lined up in races over the winter. Some of the top racers are riding at the very top level. Leandro Messineo (one of the very top ranked Zwift racers) is currently racing the Vuelta a San Juan along side the likes of Peter Sagan.
In the winter it’s a safe way to keep up the hours. Yesterday I did a 100km Z2 ride on Zwift. There is no way I’d have been ale to stay focussed for that length of time on TrainerRoad.
Zwift racing is only set to become bigger and more popular. There’s a new breed of rider, the indoor specialist, becoming apparent. And some of these indoor specialist are also pretty handy on a bike in real life.