In the early 00s, someone -- I have no idea who it was so I'm gonna blame Cory Doctorow -- read in a brand guideline document somewhere that you're not supposed to pluralize "Lego." They interpreted this to mean that you use "Lego" to refer to both one Lego brick and several Lego bricks. This idea spread like wildfire, because this era was Peak Pedant Worship on the internet. In 2005, a grammar nazi going on an angry rant about something technically incorrect was the coolest person in the world.