Absolutely don't agree. I'm a tab hoarder (currently have 2084 tabs). I don't use builtin browser facilities, but instead use sideberry. I've tried a lot of other tab mgmt approaches too. Some were excellent, some were far from it.
The one thing they all have in common: they cannot stop me from being tab hoarder. That behavior (in my case, and I suspect I am not alone) is not impacted by tab/bookmark mgmt approaches, at least not by anything I've seen.
I tried Sidebery for a while among other vertical tab extensions and found them all too flaky and tacked-on-feeling for my taste. Needing to edit userCSS to hide the redundant tab bar kind of sucked too. Now I don't use vertical tabs unless the browser has them built in as a first-class feature.
The one thing they all have in common: they cannot stop me from being tab hoarder. That behavior (in my case, and I suspect I am not alone) is not impacted by tab/bookmark mgmt approaches, at least not by anything I've seen.