A few of points:
- it is possible to get Chrome to misbehave and to dominate CPU usage with a minimal number of open tabs; I don't know about FireFox because I don't use it often (it is deficient, for me, in a number of other ways).
- I agree that, as a solution, reinstalling the OS is a poor choice, partly because people tend to migrate or reinstall things that might have caused the original problem; and because it is time-consuming and ignores diagnosis and troubleshooting.
- Third-party add-ons, particularly those that launch with the System, are greatly suspect, but rarely discussed.
In recent years, these discussions have seemed to lean more toward, "why is Apple the problem?", than reflecting on systematic troubleshooting. Maybe there's a place for that; people have to find a place to vent their frustrations. But, for instance, if I had two cars that I fueled at the same gas station, and one always had problems with bad fuel, but the other ran reasonably well, would I blame the car or the fuel?
So is the symptom of using excessive RAM in Safari with multiple tabs open due to Safari alone? ...or to some persistent HTML in one of the tabs? ...or to a 3rd party process (initiated by, or independent of, a web page) conflicting with one of Safari's processes? And if the problem is with the HTML or another running process, is it a problem because Safari has a bug, or the because HTML or the process makes a questionable programming call?
I'm not trying to defend Apple here. I'm trying to point out that the issue is complex enough so that one can't easily assign blame. I'm also not dissing you - this is a frustrating problem that takes a lot of effort to solve, so I can understand you wanting to blame Apple.
Right now, I'm running 19 open tabs and Safari drifts between 2% and 6% CPU (while two Google Chrome Renderer processes consume more than 20%). I still have a few intermittant problems, but have eliminated most instances by using some of the suggestions in this discussion.