MeowChat is not a new invention. It came into to popular use on the rec.pets.cats.community (RPCC) Usenet group. The RPCC group itself came in to being around 1994, when rec.pets.cats split into several subgroups (rec.pets.cats.anecdotes, rec.pets.cats.health+behav, rec.pets.cats.community, rec.pets.cats.rescue, etc).
The RPCC philosophy is that since cats are superior creatures, they have no need to adhere to such human standards a spelling and grammar. Some RPCC posts are written in standard English, others use varying degrees of MeowChat. An example from October of 2019 is:
Hmmm, dat all looks really good. Sarge, Lucky, Sammy, you want to join us? [The kitties hit the buffer table, and come away with plates heaped high with roast beast, grilled fishies, a couple different flavors of Fancy Feets, some grilled ear of sooven, and some Mousicles.
It has been suggested that MeowChat is a form of derivative of LolChat, made popular by sites such as icanhascheezburger.com. In fact MeowChat had been in existence and in common use for decades before icanhascheezburger.com ever appeared.