You know, Steam do it mainly because phishing, spam and scammer; as they say. I think there's another reason for this: increase the perceived value a customer may have about their account.

Facebook is probably the ultimate platform in terms of private data gathering and huge number of individual registered... yet, the average people value their facebook account more or less pretty much as the contact list on their smarphone: its important only when you have to contact people somehow; other than that, pretty much forgettable.

Steam, instead, with their account system had probably lured many people who resort on piracy to switch over them... pushing them all the way to the unimaginable: spend money. Even only for "unlock" their account.

You can think to erase your Facebook account any time; maybe thinking to give your new account's contact to "only the people you trust".. but in fact, this is the proof that your Facebook account may get "dirty with useless junk": no matter how many FB account you have, you always think those stuff can end in your trashbin with no regrets.

Your Steam account? Its a bit different. Its not just about a bunch of photos/video/meme you can download and repost in any other alike service. Its something you growth by luck (games that went for free only once), time (save games kept tidy and clean in could storage) and, finally, with money.

(own) Money have the power to increase the value of something, since its limited how much you can spend... it forces your brain to be very cautions about it. People tend to "forget about itch" until they don't put some into. I do seriously doubt that Apple as "fan by sympathy" and most Apple fans are, in fact, customer who have invested lot of money on Apple's subpar product (and they will find offensive the word "subpar" because it touch something really inner themselves, personal).

But my suggestion is not to just copy the Valve's system. My idea-feedback is to make this actually count for something. Itch account's extended features may come in two modality:

1) Classic "spend/put 5$ from your itch wallet" (copy/paste from valve)

2) Special "Itch 5$ abilitation package". Basically a special bundle (different games each month) that give you great games at discount price if you register to Itch and have your account enabled straight away. If you're already registered/abilitated you gain an additional discout on the 5$ (3~4$? )to get the same bundle at lower price

First idea only works if the company is rich to do such a thing, you do not see this happening anywhere else not even in GOG. Discount only hurt developers, steam ??% (remamber there is no 30% and developers can not say the numbers because they sign a contract) plus the X% cut means less money. This will never work, it wont work on itch since X% can be anywhere to 0-100 this just means less money on what they already are ok to give to itch.io site.

Thanks for your insight, I'll be here for other people's opinions too.

People don't spend money to unlock accounts.  They spend money because of Steam sales, insane bundle deals, and so on.  Most of the spam/etc accounts are 'botter' accounts that farm trading cards; primarily based on the Russian and Asian (Chinese primarily) markets.

SidAlpha did an in-depth video on the underground 'industry' behind trading card farming & automated selling.  Game 'developers' (asset flippers) spam Steam with dozens of games and get trading cards for them through affiliated (corrupt) publishers that auto-enable trading cards on their new games.

Once that is done, the game dev sells keys for like 5 cents each in bulk packs of 100 or 1000+ to trading card bot farmers who end up making their money back within hours or (at most) days.  Once that is done the rest is pure profit for all parties involved.  Developers passively gain a few US cents (with a minimum of 1 US cent) per sale and you can keep farming over and over and over and over.  Just let it idle on a menu and no need to really do anything.

It is trivial to buy black market stolen financial credentials (credit cards primarily) and use them to verify steam accounts and then farm as many cards as possible and sell them as quick as possible before the inevitable chargeback (if it ever even gets noticed; most people won't notice a random $5 Steam charge).

So please; let's not put any of that bollocks on the itch.io marketplace.  If you want itch.io to act more like Steam then just go pay your $100 fee and 30% royalties to the great Lord Gaben (lol) and grovel at his feet when he deigns to feed you the scraps left from your meagre Steam sales.
As a budding game dev and a consumer/gamer, I am here because this place is NOT like Steam.  Currently itch.io cut is completely optional/variable depending on what game devs want to contribute so expecting extra features cannot come unless a mandatory minimum fee/royalty is reinstated.

Doing this would destroy itch. itch was built to be free for everyone, but if it suddenly became paid or required it to be bought if devs wanted to actually sell their game, itch.io would be completely abandoned because it basically only has indie devs.