The "old UI circa 2010" is like the second refresh, and the game already had the reputation back in 2007 when I started playing. It refers to the big business players, who actually play the game like they're real life companies.
I was guessing at the date, because I started shortly after launch when I was a wee lad. The way I remember it is the joke was because of the way every window had rows and boxes, with data inside. I don't actually recall people using actual excel spreadsheets for much other than enjoying the meme because a lot of the things we use excel for in industry now did not exist yet at the time. (Maybe comparing ship stats before the compare tool got better?)
I'm not so much arguing with you as presenting how I remember it. We could both be right, or one or the other, it's not important... I'm just an old scordite miner getting ready to retire, so out of the generosity in my heart, anybody who sends me some ISK today, I'll go ahead and double it - no strings attached. It's time to get out of the game anyway.