What’s the most common rejection reason you’ve seen?
TL;DR... probably not a common one, but I got rejected for not meeting their PR / traffic requirements...
Details...
Back in my SEO beginnings (around 2011??) I had a website in the medical industry (the "bed wetting" niche more specifically) that I've set up and built from scratch, manually (including customizing the theme, writing and optimizing the content, etc..)
And in a month or so (back then it was still fairly easy to rank in google fast, without much money and in heavily regulated industries like health & medical... although, back then they probably weren't that regulated given that I could rank in those industries so fast and easily)... but anyway, back then I started ranking this site in google for some keywords and getting a fair bit of traffic, not much (I think around 250 uniques a month IIRC), but it was consistent traffic (and growing little by little) for a few months straight...
And then I outreached to a few sites to ask for a guest post and one of the sites that replied to my message had said something along the lines of "hey, you've got a nice site, it really shows that you've put effort into it" (I think that I've told them in the first message that I've built this site from scratch all by myself because I was "heavily passionate about this niche" or something, and my effort clearly showed anyway, both in the site design and the content quality)...
So anyway, back to their reply... "we can see that your site is great and that you've put effort into it, we also have no doubt that you'll be offering us quality content, but the manager of our editorial team has specifically instructed us to accept content only from sites with PR of 4 or higher, and with organic traffic of at least 1000+ per month..."
Back then PR was still a thing and the PR of my site - while I don't remember the exact number - I think was less than 2, possibly less than 1 as I don't think that I've gotten too many backlinks for that website... or too many quality ones anyway...
So anyway, long story short, they're rejected me because the site didn't meet their PR and traffic requirements, but they've assured me that once I meet those thresholds I can contact them again and they'll happily accept my guest post...
I never got to contacting them again as I sold the website in the meantime, but yeah... that's one of the reasons for rejection that I can remember of... probably not a common one, but I think you've already covered all of the common reasons, so I didn't want to mention them too
