It may seem like a silly feature, but it is quite useful.
Example: When using a computer that is not ours (or not) and searching by opening several tabs (search results from Google, Bing, Youtube and others), sometimes we accidentally close a tab and do not remember which site or which linkwe click that it was closed.
Here is an example gif in Internet Explorer:
Here is an example gif in Firefox:
In Firefox, you still have a history panel, even if you are in private browsing.A resource to consider.