@adam_caudill I think the main driver is greater inclusivity. We can see from Mastodon and certain corners of the online world, that there are still plenty of people who think and write in complete sentences.

In the past, good writers were probably self selecting as people interested in online life. Nobody merely dabbled in online communities. You were all-in or you cared nothing for it. In some circles, there was a social cost you incurred when people found out that you were one of the weirdos who talked to strangers through your computer.

There was also self selection based on geography and primary languages because of dial-up limitations and unreliable broadband. Now it's common to find out the person who's been writing you tone deaf messages is from the other side of the world and doesn't actually speak your language in daily life.

I do think that our attention spans are indeed shorter overall though. I just don't see it as the primary reason for why online conversation looks the way it does today.