Too many ways for the same people to communicate.
For a brief, halcyon period, everything went to email. Keeping up with communication with important contacts, at home or at work, meant keeping up with your email. If there was too much, you applied sorting rules and so on.
Now I get the same conversation happening partly on email, partly in WhatsApp, on Teams at work, sometimes in SMS (OK not strictly the Internet) and maybe in FB Messenger as well. And I've been forced onto all those systems, sometimes specifically against my better judgment, because I need to communicate.
I want someone to invent something that brings all messaging together into a single client. Preferably called Pegasus Mail or something.
I think the rot really set in around the time AIM was invented.
Mail and news (and later, RSS) all integrate pretty well in an appropriate client, as they have the same here-are-some-messages-for-you-to-read paradigm. This is why web forums are bad, forcing you to read messages on someone's website rather than in your message-reading tool of choice.
All the IRC-like things also integrate pretty well in a sufficiently capable client. Trillian and Pidgin dug us out of the fragmentation caused by everyone re-inventing ICQ.
SMS gets a pass for being a non-internet thing, but the various attempts to re-invent SMS as either an IRC-like-thing (WhatsApp, Signal, etc) or a blogging platform (Twitter) leave you with this awkward middle ground. Slack brought IRC kicking and screaming into the Century of the Fruitbat, and then did the usual social media bastards thing of ditching the interoperability. Simialrly, Discord's pretty good, even if nobody really knows what it's trying to be.
And then there's the corporate stuff, where if it wasn't invented by Microsoft, it has to be a second-rate proprietary product from some company you've never heard of.
The pandemic stirred it up by making people who weren't used to collaborating via computers decide that video conferencing was the best was to collaborate via computers. Zoom had the right product at the right time. Teams was made by Microsoft (see above). Some people had Facetime available because iPads are the least-pain way of letting grandparents loose on the internet. And everyone else seems to use Whataspp, which is awful at video, but Facebook has trained people to expect minimum viable usability.
It's a mess, and there's no coming back from it. Maybe things will swing away from monolithic walled-garden providers for a bit as Facebook dies, but the great thing about standards is that there are so many to choose from. More likely, I see SMTP-based email (surely the last truly open standard) dying a death of a thousand over-enthusiastic spam filters - eventually, if you want to message someone on google mail, you'll need a google mail account.