[azangru]

> I've been able to achieve compatibility down to IE3, and hoping to go down all the way to 1.0, as a lone developer writing a relatively complex project.

You are perfectly free to spend you time as you see fit; however, you might notice that many projects are dropping support of old browsers. This frees up developer resources, helps with the writing of cleaner code — e.g. CSS grid as opposed to tables or floats; js modules rather than huge js files or complex bundlers; web components instead of imperative handling of all the update logic — and opens up new possibilities in the browser including the webassembly. This is clearly a win for developers; but it also ends up being a win for users.