It's a signal they want to put out that they don't respect the rules of grammar.

They'll grow out of it and one-day look back and cringe, as we all tend to do eventually.

It's really hard to read. There's "text-transform: capitalize;" which puts things in Title Case but unfortunately that is also hard to read for body text. ( That Was a Trend Too For a While If You Remember. ).

hitting upper case on each word doesn't feel ergonomic but rather aesthetical. if we have periods, why do we need upper case? or why we don't have auto-capitalize globally activated in every text-box? as someone who type like this on my blog; i refuse to hit shift everytime i bring a period into any text, as well not using period at the end of any paragraph and not capitalizing "i", because otherwise, i want "YOU" and "WE" and "HE" and "THOU /j