I like treating my online identities the same as emails: personal, work and anonymous. Depending on the platform I then choose a specific direction for each account.

On Instagram I have two accounts: photography focused and triathlon focused. I only post photos that reflect those activities.

On YouTube I also have two accounts: one for watching all kinds of random videos and one for watching work, or personal development videos. This helps YouTube algorithm serve me better recommendations based on the mode I’m in: relaxing or working.

On Facebook I only have one, because it is tied to my actual identity. I use it only to stay in touch (contact list) with friends and family. I rarely post there though. It is a great tool to wish Happy Birthday though.

On Reddit I have two accounts: personal and anonymous. I use personal for posting travel photos, anonymous for everything else.

For me, there are clear benefits of having multiple accounts. I do hope I’m that switching between accounts keep getting better.

Yea YouTube doesn't reward versatility. One of the channels I sub to used to have one channel for both their gaming and vlogging videos. Apparently it wasn't working so they made a second channel just for gaming videos and the original channel will now only be for IRL videos (vlogs).

I have 2.
I usually use the informal version of my first name with the first letter of my last name as here on Cake. On sites where that is already used I might append NZ which is the country code for New Zealand. Anyone with half an idea could link together my accounts in different places online.
For me that means I am aware that whatever I post can be traced back to me as a specific individual and so to some degree it ensures I behave nicely online. It also means I can be called out on anything I have posted, ever, so I have to be able to stand by what I have posted, and so I only post what I can stand by, if that makes sense.

My other persona is for my New Zealand specific adventure riding website and is only really used online on Youtube for a separate channel.

I can understand why some people would need anonymity but most people don't. Personally I have no need to hide behind a pseudonym, I am who I am and that's who you get.

I have multiple accounts on Twitter, many of which have a corresponding Facebook like page: A personal account (same slamdunk406 handle on Facebook, Instagram, and Twitter as what I have here on Cake), accounts for my NBA and tennis blogs, I set up a Michael Jackson fan account and Prince fan account, and I also have something set up for the NFL. Couple others as well. All of those Twitter accounts link back to my personal Twitter account, so it’s clear it’s me.

I also have a personal YouTube channel, LinkedIn account, and of course Facebook profile. I have fun writing under the different banners I have, but I still like them to all link back to me. Just so that it draws more attention to me personally and also so that everything is more nice and tidy.

That said, I also see the value in writing stuff anonymously.