It's not only due to the people working on the site, but those paying to have it made too. A lot of clients also associate 'fancy' and 'complicated' with good, and then end up demanding every every feature and gimmick you can imagine in some attempt to look 'modern'.

So you end up with the designers, developers, content editors, SEOs, managers and clients all wanting different things at once, and none of them want to remove what's already there to lighten the load.