Sometimes, no amount of optimization will achieve your performance objectives with the "obvious" path and you quickly find yourself deep in diminishing returns.
Sometimes, you really do have to do an extraordinary amount of work and cover an intimidating minefield of edge cases and heisenbugs to achieve a viable, working solution.
Of course it's almost always better to use a DOM library and just be done. Of course implementing copy+paste and drag-and-drop on Canvas is a masochistic slog. Nobody wants to do this; not even the insane.
The question is whether when the need arises and you've exhausted all other avenues, can you engineer the hard solution?
I remember browsers starting to not love dynamic tables with just some thousands of rows.
Source: I built a virtual table implementation a decade ago that scaled just fine to tens of thousands of rows, and browsers were a lot slower back then. But my requirements were also relatively simple, so YMMV.
Edit: It also is not exactly the poster child of good UX and accessibility (or even performance, for that matter), so I'm not sure it's the best example.
