Only weak players go to the net when they dont have to.
Define "weak" [are you talking a certain NTRP/UTR or do you mean relative to the opponent or something else?].
Define "when they don't have to": under what circumstances would you say one "has" to come to the net [ie the most extreme example would be a well-hit drop shot but even then, someone could pick it up and then try to retreat. That would be terrible tactics but it's still possible.
I come to the net "when I don't have to" because my net game is better than my BL game [something you failed to consider]. Whether I'm "weak" depends on what scale someone is using to judge me.
When you go to the net you are losing control over the point.
I never necessarily had control to begin with. At best, I was neutral.
Going to the net forces the issue in the same way hitting a great GS does: it puts the opponent in a position where a neutral shot [the most common] is no longer optimal, either because I'll be in a position to put away a volley or because he got pulled out so wide that it makes sense to go for a great shot into a corner.
So, in that sense, the balance of a BL rally is destroyed. I don't know if I'd call that "losing control".
However, no matter what phrase is used, it's often a successful tactic for me.
If you play against a good defender(it means that he can perfectly play passing shots) there is no chance to beat him going frequently to the net.
I've never played against anyone so good that he can perfectly play passing shots every time. The key is, how well can I pressure him? The better he is, the better he'll be able to execute passing shots. The matches I've lost were where his passing shots were better than my net game. Still, even with this terrible strategy, my singles winning % is about 60%.
Also, being a good defender while the other guy is on the BL can be different from being a good defender while he's at net. I've played guys who could out-rally me but when I come to the net, their effectiveness drops and their error rate goes up. Yes, I get passed; sometimes, a lot. That's the way I choose to play the game based on my strengths and weaknesses.
You have to beat him using angles and power. If you cant generate great speed and angles you are just losing.
I don't need great ball speed to win if I'm in a good position at the net. You're only looking at it from one viewpoint.
I call my style "active defence" and I cant remember when I lost to player who played serve and volley.
All that means is that your passing game was better than their net game, not that coming to the net is universally a bad strategy. I will readily admit that when I lose, that's usually the case.