You don’t have to be a paying member to be a Premium member...
I think the non-paying membership is called ‘Basic Membership' nowadays. On the old site a 'reviewer' level member could read and review everything. On the new site we can only join a single group. I have access to the Premium group. I’m not sure if that is a legacy thing or normal for ‘basic membership’.
On the front page I am offered “New Writing to Review from Your Groups” and I assume this is only content from the Premium Group. I can read and review competition entries.The content within the specific groups is listed and available to read and review, but I have to go look for it(not in-line review, but those reviews are for editors, no readers so it makes sense). I can’t join the groups, but I guess that only need apply to writers who want to submit work to those groups?
Ah, I expect you are right about a legacy membership. I know after my initial week's premium membership ended, I had to pay a subscription to be able to post anything here in the forum, enter the competitions, post any content, etc.
I am not sure I agree with you about readers and inline reviews. Sometimes it might be useful for you to highlight a specific bit of writing that doesn't make sense to you. Maybe you can't work out who's talking, maybe you are not sure where you are, or anything else that is concerned with the readibility of the piece, rather than the nitty gritty of line editing. For me, that developmental editing is as useful from a reader as it is from a fellow writer. I am so sorry you have been burned and I won't get the pleasure of seeing what you think of my writing.