15 years ago, it was incredibly common to see folks texting things like "c u ltr". It made its way into instant messaging (where folks had a keyboard), but slowly disappeared once everyone had smartphones that autocorrected everything. I don't think it's strange to see that people prefer it stylistically. Text has very little in the way of showing emotions or intentions, so everything you can do to alter that is something to be used. People want to be less formal sometimes.