[forgotmypw17]

Get some historic perspective. The classic older browsers will run easily in Wine or VirtualBox. Try to build a website for Mosaic. And upgrade it for Netscape 2.0 and IE 3.0. Then upgrade it for Netscape 4 and IE 4, while retaining compatibility. And onwards to today. If you can span 25 years of it, you'll know more than most of today's web devs by a long margin. It is easier than it sounds, especially if you start basic.

[nodelessness]

No. You won't know more than the average web dev by a large margin. You will know very little of what is possible today and some things that are outdated and not relevant any more which are going to be useful in very rare situations.

[forgotmypw17]

Knowing what to do in rare situation is what separates an advanced practitioner from an expert.

[xupybd]

No it doesn't. Knowing how to solve real problems is what makes you an expert.

Who cares if you can make a website with early 90s browsers. That's a skill that is obsolete. It might be fun but it doesn't make you a better engineer.