This is intentional as it is a way to protect against finger printing your browser window based on the dimensions of going full screen. It reduces the websites ability to track you based on the window dimensions.
Most onion services are not running on servers. The are running on PC's, laptops, raspberry pi's etc. If the person running it turns off their machine, then the website is down.
Troubleshooting an onion service is just like any other website. If you can get to onion site A but not onion site B, C, or D it is because those are down.
You are correct, if everyone had these plugins then everyone would look the same.
However, let me share a couple of quotes:
From the FAQ:
Some people have suggested we include ad-blocking software or
anti-tracking software with Tor Browser. Right now, we do not think
that's such a good idea. Tor Browser aims to provide sufficient
privacy that ...
Google your laptop model for the key needed for the boot menu. They can vary greatly depending on who made your laptop. For example, MSI laptop uses F11. My Thinkpad uses Enter and then F12. My desktop uses only F12.
If you have a very old computer, you may need to change the boot option in the BIOS. We can't tell you what that would be so you will need to ...