In a bad marriage, you can feel more lonely than the most single person in the world.
In a big family, or in a suffocating relationship, you can dream to be alone because you need me-time to recharge the batteries, especially if you're an introvert.
It's true that humans do better in relationships that alone, but taking on long drives by yourself can be better than seeing a psychologist; reference: I rode motorcycles for 15+ years, and I've travelled the world. I miss it dearly. There is something to be said about experiencing the world for yourself and without sharing it.
- "don't write about him, don't try to describe him, just watch him."
replace "him" and substitute with something you enjoy.
Then there are people that thoroughly enjoy being by themselves. It doesn't mean that they don't ever need company, just a lot of the time they feel a bliss being by themselves doing their own business. There is no overlap with that feeling and loneliness.
now, being alone (stationary) isn't the same as doing an activity alone. you seem to conflate the two. if you think traveling solo is fun, well you're being sold bullshit at best, worst you're acquiescing to a terrible experience and trying to find joy in it. like a prisoner-author talking about the joys of being locked up because it afforded them the necessary solitude to contemplate.
Maybe, just maybe, people experience things differently than you, ever thought about that?
And even if it would be about loneliness, there's nothing wrong in connecting with people over internet.
I do think everyone should travel alone at least once. I allows you to discover yourself.