I do think forum topic makes a difference. I used to be on one - in the days when forums were huge. That was completely private and paid membership only - due to legal situations. Not only that it was female only. And you were required to not only pay an annual membership fee but give your name and address as well as your email so you could be verified as really living there. It was a huge forum. Nothing on google as it was private - they did PR interviews and got articles posted in newspapers and magazines instead.
Yet so many people wanted to join that forum they put up with all that. The owner gave it up about 10 years ago. There's another one I can think of that is very large and very active and I don't think anything would deter people from that one because the topic is something they are fascinated by and it's the main forum on the topic. Maybe curiosity beats impatience sometimes.
However it is a real point that any delays getting onto a site and people give up and move on. I think there's a difference between a slow loading site that takes a while to get going - and a quick flash of security check. I think Cloudflare challenges annoy just about everyone - but they are on most sites now. It's the thing that grates the most with me - I don't want everyone having a cloudflare challenge, so I've minimised who gets it - but some will get it. And some (not many) will get a button to click straight after, but it has a friendly html page and message and less impersonal than a cloudflare page.
My home page articles are the big attraction on my site - they get found on google a lot. And everyone can see those. Although these days I get a lot from google going straight to a thread as well.
I agree though that the number of registrations doesn't equal activity. I get lots of registrations, but only a small group of regular posters and a lot who come, post, a couple of times and go once they've got the info needed - that's the nature of the site partly - it's informational as well as being a community. But as all people who register get a welcome message asking them to introduce themselves that encourages some to post and get involved who would normally just read and go. Most of them are on Instagram or Reddit - but some come to my site from there as well.
I had a couple of new members recently who said they were so happy a forum still existed on the topic as Facebook is harsh on the topic and not as nice to use sometimes.
As for the bots - yes it's a bit scary what will happen next. I mean if can they take over refrigerators all over Europe! I think it's becoming a big issue and known about and some kind of legislation will have to happen to curb things.
There are newspaper articles all over the internet about all the "are you human" challenges everyone is facing - I can't find the one I read the other day, but humans using the internet know about it - they're not surprised to find it on every site these days. The most annoying ones (and I personally find this) are the captchas asking you to move an animal into the right position and match the picture. There is one site I go on that has me do a captcha matching vegetables in a basket three times when entering my email address to log in, then another three times when I enter my password to login - I actually emailed them and complained and said 6 picture captchas just to login is ridiculous.
The Cloudflare managed challenge is at least quick, if ugly - it's a whole page. Unless someone gets stuck in a loop and there are a lot of complaints about that all over the internet as well. People aren't frustrated with our forums - they are frustrated with the internet generally.
"Captchas and other bot tests are now ubiquitous. Cloudflare, which relies on other tests such as the “verify you are a human” tick boxes, says it now carries out 7.7 billion anti-bot checks a day, up from 2.1 billion in 2023."
"Some sites are taking more drastic measures, such as demanding users sign up for accounts or log in more frequently to prove they are human."
"Humans are now a minority on the web. Proving that you are one of them is going to get harder."
Daily Telegraph Article - Why the Internet is becoming so infuriating to use
I.e. Facebook and Pinterest have proven ages ago already that limited guest access does not hinder success. Registering is a bit an inconvenice, but will on the other hand sort out people who are not really interested in the platform.
