Wut 1S wif peeple

I keep looking at forums and youtube and I am just trying to understand why everyone is too good for proper grammar, spelling, or even to keep numbers out of words. Anyone that is able to provide some sort of reason will be my new best friend, or BFF 1F i wanna stik wif dis new slang. I think that the part that's the most confusing to me is it has to take longer to write a response with numbers and random caps than not, so it can't even be laziness that causes this.