No, from a purely objective perspective, it’s definitely a viable strategy to deny resources from your enemies. That’s how many RTS games are won, for example.
However, in the context of playing a multiplayer game, we also have a responsibility towards other players. Everyone plays this game to have fun. Denying fun from your fellow players is inconsiderate and selfish. Even if it’s not against the rules, if people aren’t having fun, the game loses its point.
Some collectible card games and tabletop miniatures games have builds that let one player win by basically not letting the other player play at all. That’s all well within the game rules. However, even though winning may feel satisfying, no decent person should find enjoyment from defeating someone who was unable to even make a meaningful move.
Online gaming is worse than tabletop gaming because online, you don’t even see the other player. It’s easier to forget they’re a real person, easier to forget that they’d like to have fun too.
That’s the main reason why I play Single-Player. I don’t want anyone else to be responsible for my fun, and I don’t want to be responsible for anyone else’s fun.
Remember: even if you’re playing against other people, you’re also playing with other people.