Yeah, if you configure the laptop on Dells website, you can choose Ubuntu for some models.
I would love to see more Linux notebooks on third party online shops and offline stores. Not just from Dell, but also other vendors.
In my whole life, I never saw a Linux notebook in any local store. I'm living in Germany, so the situation might be different somewhere else, but I asume it's the same in whole Europe and north America.
It's a more than 4 years old blog post.
I can't tell much about the things that the writer complains about. But concerning Cosmic: I think a new additional DE is a win. People who like it can use it, others can skip it. More variation means more choice.
Personally: I find Cosmic still a bit barebone. It is very fast. It think it looks quite good (besides their wallpapers). It's not yet there, where it needs to be for me to use it as a daily driver, but I find it impressive what System 76 released in their first final version.
Gnome is the most beautyful DE in my opinion, but I find it's UX absolut horrible. I hate usining it without quite some extensions and I do absolutely not use it. Look at it, yeah. But using it is not intuitive at all for me.
Luckily, there are other DE's I like. That's the beauty about Linux.