> I think you need an invitation to create an account,
Anybody can create an account on arXiv.[1][2] However, having an account and uploading are different things. Strictly speaking, you have to be endorsed to submit a paper. But some endorsements are granted automatically, based on various criteria. So not everybody has to go explicitly ask people for an endorsement:
arXiv requires that users be endorsed before submitting their first paper to a category.
arXiv may give some people automatic endorsements based on subject area, topic, previous submissions, and academic affiliation. In most cases, automatic endorsement is given to authors from known academic institutions and research facilities.
Generally speaking, the "word on the street" is that it's as simple as "register with a .edu email address and you get auto endorsed, otherwise you don't." But I think the reality is slightly more complex than that. Although the exact details are kept private, probably at least in part to prevent people from gaming the system.
Note that the page encourages you to register with an "institutional" email address, but doesn't specifically say it has to be a .edu one.
arXiv submitters are therefore encouraged to associate an institutional email address, if they have one, with their arXiv account. This will expedite the endorsement process.
I think you're right to nitpick, but nitpicking the wrong thing.
> and not send it to any journal.
This, doesn't matter.
The main point of my comment is "journal != peers reading the work". Which, of course, you could even say is true about ArXiv (fine to nitpick[0]). You can put on ArXiv and no one will read it or the only people who read it are not peers. You're right that submitting to a journal or conference (nearly) guarantees someone has read the paper.
The thing though is "peer" is weakly defined. I recognize that it is contextually defined, but I'd hope from the context of my comment you can tell that I'm using "peer" to mean "another person well versed in the niche topic of the paper." This is different from "a person well versed in the topic of the paper." The niche matters. I explain more in this comment[1]
Or to put it differently, just because someone read it doesn't mean they /read/ it.
[0] I'll revise the quoted text to "Just because it is on ArXiv doesn't mean peers aren't or haven't reviewed it". Though we can nitpick a little more and say that if there are more than one author on the paper, a peer has been much more likely to have reviewed the work (not all co-authors review the works they are authors on...)
> Putting the paper on ArXiv does mean peers are reviewing it.
You can upload a pdf to the ArXiv and not send it to any journal. I think you need an invitation to create an account, but it's 99% like WordPress.