I use this crap to order repeat prescriptions and it always annoyed me that they couldn't spell it correctly. But I think I worked out why they did it and it turns out to be a monumental lack of imagination.
systemone.com was registered back in 1995. So I assume that some naming council under the guidance of a steering committee at TPP, having spent 3 years on coming up with systemone as the name, then had to throw it back to an emergency focus group who only had six months to find an alternative. Then some genius realised that it kind of sounded the same if you dropped the "e" from system.
It took me nearly an hour to press submit on this as I went over every single spelling dozens of times. There is nothing worse than taking the piss out of spelling mistakes, only to make even more of them yourself. Please go to town on me if you find any as I definitely deserve it.