Saving 100s of tabs isn't going to work either, unless you can remember the name of the window and then tediously look through the list of open tabs. In that case, just search through your history instead of having the tabs.
Not everyone's memory works the same way, and not everyone's organizational skills are the same. Whereas (it sounds like) you remember a task you're trying to do, and then go do it, and make a new tab and go do the task, for others, coming across the tab itself serves as the reminder about the task, and a call to action to do it. I'll open a tab that I need to do X, forget about X/procrastinate about X, open a tab for Y, and then Z, and then through going to a random tab, get to the tab about X, get reminded about doing X, and then go do it.
Sure It can. For example, If I'm looking for a certain stackoverflow post about a project I'm working on, I know it's be on the window with the other resources for that project, and I can remember that it's roughly on the middle right portion of that group of tabs. That narrows it down to <10 tabs to quickly check.
If I use my browser history, I'm going to have to re-filter out all of the webpages I deemed inadequate. If the tab was left open, I know it was at least somewhat useful.
Firefox switch to tab, my friend. You open a new tab, start typing the title of the page or the address of the site and it shows up in autocomplete with a switch to tab indicator and when selected it moves you to that tab instead of opening a copy.