I understand

If this info is of any help:

The biggest cycling forum in my native language (under 100 posts per day, so far from a high traffic site) uses a policy that new users must have their first 3 posts manually approved by the mods.
It's a bit more hassle, but works for filtering out any spammers, without image-posting (and link-posting) restrictions (though I suppose that's not a good idea for a really high traffic forum).

For bikeforums, here's how to post an image by using imgbb website link, but removing the "https://" part and placing a blank space (" ") after every dot ("."), so it doesn't look like a link either (members should be able to figure it out from this).
i. ibb. co/mC3t1N2/brooks-flyer. jpg

Here, I wrote a brief tutorial on how to post a picture to bikeforums

Also newbie here. This seems hard from the newbie's point of view, but after the above Mod's experiences the policy is understandable.

As a newbie, I also find this requirement quite onerous, even if understandable from a certain point of view. I'm being evicted from my rental at short notice, and have to sell or give away a lot of stuff in a hurry. Some people recommended this site as the best place to get a valuation of my precious old bike. The pressure of having to post ten times in this forum (and no more than five posts in a 24 hour period), before I can even post photos of my bike makes a simple thing suddenly extra difficult. Just my 2c.

This is an odd complaint because someone posted your photos within an hour of your first post inquiring about the bike.
You actually got the "emergency" posting, but in such a way that someone could verify that you weren't a bot or spammer before it went up.

If you've ever tried to use a internet forum that doesn't have such protections, you'll find they don't last very long as they quickly get overrun with bot traffic and spam. .