If you made a website in the 90s or early noughts, everything was tables. Do you remember how to make a button with a bevel in 2005? You made a 3x3 table, and had to splice an image into 9 different sub images, and then stitch them all together. Now you have background:linear-gradient and border-radius. I mean, maybe you take this for granted now, but seriously, that was game changing for me when those things came out.
Now add on UI frameworks like Bootstrap and Zurb. Before everything was a JPG photoshop mockup. Every design was treated in isolation. There were entire businesses revolved around taking a PSD and turning it into HTML/CSS. Now everything is a component. It's reusable...and useable. Sure, we may have watered down design to the point where largely every SaaS landing page is the same, but the speed with which we can get developers to convey trust via design is vastly improved over the old days.
Sure, JS frameworks are all the rage right now. But we have made serious strides in web UIs as well.