If you set Can I Use to hide browsers with less than 1% usage, you hide 11.86% of the world.

If we extrapolate that to the world population, that comes out to ≈900 million people, or 3 times the population of the United States. (If roughly half the earth has internet access as of 2018, then one-and-a-half USAs.)

Your site won’t download intact

You can’t predict what will be mangled or waylaid by terrible ad code, content-blockers, DNS issues, browser bugs, privacy enforcers, meddling ISPs, corporate firewalls, or developer error.

Browsers are starting this fun new thing called user-agent interventions, where they mess with your code.

Chrome waits up to 3 seconds for any given web font. Turns out, on slow connections, most web font requests actually hit the timeout

—Chrome Interventions Quarterly § Bail out on web fonts with an effectively slow connection

Only 0.2% of browsers appreciate a <noscript>, but 1.1% have JavaScript fail. And it’s foolish to think that remaining 0.9% is consistent for a single user, or even a single session.

Google Web Light transcodes millions of URLs. Opera Mini is still holding on with 3.3% usage. There is a real business in harshly optimizing the web.

Every browser but Chrome has a Reader View. Instapaper and other readability services are quite popular for salvaging content out of bad sites.

People insist on being unique

More users than you think change browser settings. userstyles.org’s various user-stylesheet extensions have over 2.7 million installs.

Users zoom.

And let’s not consider browser extensions and how they will absolutely mess with the DOM and your JavaScript.

About 15% of the world are considered disabled. Beyond that, people break bones, get their eyes dilated, and have other exciting accidents and conditions.

Computers are out to get you

Android Browser is dead, long live Android Chrome! Except vendors love releasing their own hacked-up versions with differences. For example, Sony’s Chrome 23 was the same as Google’s Chrome 23, except they implemented an early, crashy build of WebGL.

And boy, let’s not talk about Android screen quality. I’ve started requiring WCAG AA compliance just to make sure text is readable on the cheapest (most widespread) Androids.

No connection fulfills its ISP’s promises all of the time. Or most of the time, frankly. As 4G users increase, overall network speed drops.

The same is true of device manufacturers’ published specs. And processing speed is going down.

People will use your site how they want, and according to their means. That is wonderful, and why the Web was built.

I would even say that the % of people viewing your site the way you do rapidly approaches zilch.

The only rational solution is to build resiliently.