The problem with this feature is the user does not make the choice. Firefox should be alerting the user why they disabled the extensions and give them a choice to enable them.
How can I re-enable the add-ons that are not allowed on some websites?
We understand that installing add-ons is a user choice and, as with your security, we also take this matter very seriously. If you are aware of the associated risk and still wish to allow the add-ons that have been disallowed on a website by Mozilla, you can do it from the configuration editor (about:config):
“On display? I eventually had to go down to the cellar to find them.”
“That’s the display department.”
“With a flashlight.”
“Ah, well, the lights had probably gone.”
“So had the stairs.”
“But look, you found the notice, didn’t you?”
“Yes,” said Arthur, “yes I did. It was on display in the bottom of a locked filing cabinet stuck in a disused lavatory with a sign on the door saying ‘Beware of the Leopard.” "
If you see that an extension is blocked on a domain and don't think to Google "unblock extension domain Firefox", select an appropriate result, and follow straightforward instructions then you probably aren't capable of understanding the nuances of extension security risks.