In ‘05, you had IE6, plenty of folks still on IE5, IE5 for Mac was still in use (don’t be fooled by the name - it did not behave like IE5 on windows), safari was 2.0, respectable but still a minority browser, and Firefox was on 1.0. Plenty of folks were still on Netscape navigator, which by that point was actively decomposing.
IE6 was what you built for, as it was the majority browser by a country mile. Transparency was hit and miss. Alpha PNGs just weren’t supported, you had to hack them in via JS.
Most websites were laid out using <table>. Using a <div> was new and exotic.
Oh, and you could only do custom fonts using… flash. sIFR, if you want to delve into the hell that was web dev back then. Most folks would just end up with TNR. Transparency on sIFR you could only achieve by replicating your background into the SWF, and good luck getting it to line up.
So. Support an absolute soup of edge cases across a bunch of different browser engines, and deal with “IT LOOKS NOTHING LIKE IT DID ON THE WEBPAGE” from customers, or just do it server side.
Also, it was perfectly acceptable to wait for a website to load - 50% of the U.S. was still on dialup, and “broadband” was commonly 512k.