The alternative is having a sane process for determining what browsers you support, an a rock-solid QA and release process.

They support Edge, Chrome, Safari, and Firefox.

That's 87.86% of what users are using (per Wikimedia's stats). To support the 1.76% of IE users, it will require a disproportionate amount of work that could negatively impact other development that benefits many more people.

That's the reality: Development time is a zero-sum game. If you do this you aren't doing this other thing, and in this case we're talking about under 2% that likely should be discouraged from using it.

PS - And this coming from someone whose uses are primarily on IE11 still (see my other post in the thread). Just because I personally benefit from IE11 staying around a few more years, doesn't mean the entire web should bend to that. IE11 must die, we just cannot turn on a needle, and when Edge dropped support for Java Applets/Flash it forced tons of organizations into IE11 for many more years than they would have wanted.

Code to standards and expect the browsers to implement those standards reasonably.

Avoid the bleeding edge to support those held back at LTS versions of common browsers, or if you use new tricks make sure they don't make things unusable on older-but-LTS browsers. Whether you consider IE11 an LTS browser or not is a matter for you to decide (yes, as it will be getting security updates for some time still, or no as it is seven years old, not getting any feature/support updates, and support for it is deprecated by even its own manufacture's apps).

Support accessibility by not using fancy things for the sake of it, and if you do something fancy make at least a little effort to have things degrade gracefully for those with accessibility issues. A lot of sites/apps skip this step, but shouldn't.