As a repeater owner, people who connect and say nothing are beyond irritating.
When you connect, you are announced. Now you won't talk to us? Why did you bother connecting. And now you're going to drop the connection without saying anything? That also is announced. So all these "listen only" users are constantly connecting and disconnecting, getting announced each time, and not saying a word.
Additionally, many repeaters have a limited number (sometimes only one) of available connection slots. So you are going to now sit there and just listen, taking up a slot that a real live person could have used. And I can't call out while you are connected either, even if there are multiple slots.
Yes, connecting without saying anything is rude. If you are not going to talk on this two way medium, why are you bothering to participate at all? To say the least, if I see you connecting to my repeater and disconnecting and not saying anything when directly spoken to, you're going to end up on my blacklist and not allowed to connect at all. You wouldn't walk into a restaurant, stand in the middle of the dining room, and stare at people, and then refuse to sit at a table. You shouldn't expect to connect to a repeater via echolink and refuse to talk either.
Similarly, why would you connect and then immediately disconnect? If you're having technical difficulties with your audio, use the echolink test server until you have it fixed. If you're disconnecting because you connected and didn't immediately hear any activity, you're doing it wrong. If you want activity, put out a call. Maybe conversation just paused when your connection was announced. If you immediately disconnect without talking first, you'll never know if people were talking before you connected or if people are there but listening.
As an alternative to connecting to repeaters and listening, find a conference server instead. Conference servers have a very high number of slots, and I think they don't announce when you connect and disconnect, and won't prevent anyone from dialing out. Also, if you want to exercise your language, I can understand not wanting to initiate a conversation, but at least try to respond if someone talks to you. Amateur radio is all about communication, and I'm sure if you try you can find someone who is willing to help you stumble through and improve. Mentoring is a big part of amateur radio, but if you refuse to talk, we can't mentor you.
It is good amateur radio practice to listen before speaking. So if you connect, wait a minute or so, and then say something, that's perfect. Just don't sit there for hours, or connect and then disconnect right away, especially if someone tries to talk to you.