I appreciate this is a highly opinionated question. The issue: while IE 11 usage lowers, IE Support becomes more difficult. Is it time to take it off life support?
The option: Simply say "We don't support IE, try something better" on the home page.
The downside: Some people still hang on to IE 11 and so there is going to be some percentage of loss of use.
It seems to me, that if my site were a consumer based site, mainly for viewing purposes, then still supporting IE would be the rational thing to do. Because if someone surfs to a page, and it says "No IE Support" they will simply leave for one of many other similar sites.
But, a browser app is a different thing. It's a business app (Project Management) and I doubt there are any end users who ONLY have access to IE 11 and would thus be unable to use it at all.
But I think that most such users even if they typically use IE 11, ALSO have a second browser installed for such times when a site is not supported in IE, or it just doesn't work well in IE. (Like that every happens, right?)
In support of this is Gist.run which does not run on IE 11 (just tried it, Promise is not polyfilled.)
As a startup, I don't want to spend time/money supporting IE 11 if I don't have to. I have been supporting it, and I would like to drop it if feasible.
NetMarketshare.com says IE 11 usage is at 12.14 while w3Counter says it's at 2.71. Who to believe?
So my question is: Will I actually lose potential users by not supporting IE 11? If so, is the percentage low enough that it does not make financial sense to support it?
I am sure the question will arise, "So how many IE users do you currently have?" The answer is zero, as there have been enough issues in IE to make it an unpleasant experience.
In thinking about this, it seems to me that I can simply pull the plug on IE, and see if there are any complaints or requests for IE support. I would rather not support it at all, then support it half-baked which just makes the app look bad to end users who don't realize it's an IE 11 problem, not an app problem.
Whether you need to support IE depends on who your users are. Do they use IE? And with "users" i do not mean your current users, but your target users.
For consumers, i think as of mid 2018 I think it's fair to assume they do not use IE.
For companies, that still depends on what kind of companies. Small or young companies and startups likely use Firefox or Chrome, but bigger companies ("enterprises", more than 1000 employees) still use IE, as far as I see the situation today.
So to make the decision whether to support IE (which for sure is extra effort in development) you need to know who you're targeting.