What year do you live in? 2010? The most wanted features from CSS3 have been supported everywhere for years!

Look at the support for (flexbox)[https://caniuse.com/#search=flexbox] for instance.

In the year where not all deployment targets are using the latest Chrome and Safari.

Where there are devices beyond computers and smart phones with browsers on them, the majority of them without any kind of update system in place and based in some kind of browser implementation.

You are not familiar with web are you?

Doing web projects since 1997, coding across multiple platforms since 1986.

So not familiar with modern development? Since you don't need much CSS hacks now.

So not familiar with the fact that not everyone runs the very latest Chrome or Safari on their desktop computers, and there are other kind of devices on the field?

That's too generous. Even the things that work properly on every browser are usually hacks because HTML and CSS were made for documents rather than applications.