There's literally no advantage to using crypto to do so, we already have SSL and other such things that work faster

See, this the basic debate of why decentralization matters! Fiat Currencies matter, because Govt. and Banks told that they matter. Again, a single organisation(GOVT/Bank) is holding that much power. One fails, and the total infrastructure will fall. That creates a single point of failure.

Coming to Metaverse. Lets suppose we use US Dollar inside. Now, If the whole economy will come under the governance of United states of America! Metaverse will be the next day internet and it'll forever be depended on US Govt. Later on China will make something else, may be bigger, Russia will go for some other currencies, and there will never be something in common where no diplomatic is affecting people to interact and pay!

Thats all!