Where I work, we sell into large companies, where IE may be a default browser without the ability to install an alternative. Therefore, we support IE11 (only version of IE still officially supported). Financially, it would be irresponsible not to, as it could kill 6 or 7 figure contracts if the CEO tries to use our software and it doesn't load or just shows them a "upgrade your browser" page.

But even then, we do make allowances for IE. It is slower. In fact, some of the speed issues come from adding polyfills for things we deemed necessary for efficient development. It may not have exactly the same layout (for instance, we use an accordion to reduce the number of elements on a screen for IE on one page, but a list of carousels in browsers that are capable of handling the extra complexity).

We actually attempted to use CSS Grid, and it mostly worked. We've since stripped most of that out except some of the base page structures - just too many edge cases. And flex actually works fairly well as long as you stay away from some of the well-defined known issues.

Anyways, to the main point - has to be a site by site decision based on your site's visitor base, their browsers, and whether it makes the financial sense to spend the time supporting IE compared to the return you may get.

Which is to say, a lot of your potential customers already probably have a dozen tools they depend on that don't work in IE already anyways.

My current employer has dropped IE11 for new projects, but we keep it around for already extant products and pages, unless we do a full redesign and rethink. IE11 is such a small percentage these days that the cost/benefit ratio isn’t good.

(I only prototype stuff as a designer, so I am just throwing caution to the wind and doing whatever the Big 3 rendering engines support, because the idea of giving up grid makes me sad, now that I understand how it works. [sort of understand how it works])