We all need a moan once in a while 
All I would say is don’t give up, glide is great once you understand the concepts and how it works.
This will come from reading the docs and the posts on this forum. If you get stuck simply asking this friendly community for help.
Like any software there is a learning curve which everyone has to go through. You need to understand how the software works and whether it will meet your needs before diving in a building something (easier said than done I know)
Anyway a few bits for you below
Are you referring to this? Best to read all of it Basic plan has disappeared from pricing options
The new glide builder is a change for sure but the concepts and features are the same. The documentation is good 
You may or may not want users to sign in, depends on what you are trying to achieve. With sign in you can choose what the user will see or can do, it’s up to you as the developer to sit down and plan it out and then build it.
Conversely if glide created the initial app with user profiles you would also then get folks saying “why have you created this automatically, I don’t want this”
I have rambled on long enough now, got to take the dog out 
hopefully some of this helps.