Emphasis on "modern" --- I distinctly remember using some web chat clients with IE6 in the early 2000s, and they didn't need hundreds of megabytes of RAM (average PCs had a total of between 64 and 256MB of RAM) and the whole (single-core at the time) CPU to do what today's web apps do.

For anyone who knows what I mean, it might be interesting to write such a "lightweight" web client for e.g. Slack, restricting yourself to whatever JS abilities were available in 2000 or so, yet imitate as much of the features and appearance of the web client today as possible. Chances are it will still work with "modern" browsers too, and use a tiny fraction of the resources of the current one. All the better if it gets noticed and DMCA'd.

Oh please. I'm not about to start referring to a specific toolkit as "modern technology” at the expense of everyone else, particularly a step backwards