It's a temporary drawback; everyone wins in the long term because there's only one standard.
Again, that's not a win for anybody. No one winds up in a better position than where they started, there is no payback in exchange for the temporary drawback, which also isn't temporary if the final standard is inferior.
If some people like hip hop but more people like country, it's not a win for everybody to eliminate the hip hop radio stations so we can all listen to a single country station.
This is closer to having a common railway gauge, though.
Not at all. A common railway gauge is necessary for different parts of the rail network to be joined together. If one section of the network has a different gauge, it is cut off and can not be joined without being completely replaced, leaving you with two less capable rail networks. Everyone does benefit from a more capable rail network.
Further, rail gauge is not a consumer choice. If there were two rail gauges and your local rail station happened to have a different gauge than your destination, you'd be SOL. A different rail gauge may provide benefits for people with specific needs, but you don't get to take advantage of those benefits except by blind luck.
There is no such benefit from standardizing cable connectors. If someone charges their phone with the same style cable as you, you gain nothing. If someone uses a different cable, you lose nothing. There is no reason for anyone not to use their preferred cable which is optimal for their use case.