It's not an anachronism. Liquid markets behave verrry differently from illiquid markets.
In liquid markets, "AAPL is $141.23" makes sense. It means that you can expect to buy and sell almost as much AAPL as you want at very close to that price because there are loads of buyers and sellers near that price. You can pretend that AAPL stocks have a price like a lamp at home depot: "I would like 2 AAPL please" is a safe thing to say.
In illiquid markets, "AAPL is $141.23" does not make sense. "I would like 2 AAPL please" is not safe at all. There are bids and offers, but not necessarily a lot of them, and not necessarily near each other. If you were to place the "2 AAPL please" order (or something related like "$500 of AAPL please"), you might find that you have purchased 1 AAPL for $141.23 and 1 AAPL for $299.57 because there was a big gap in the order book. The price abstraction completely breaks down and you have to "haggle" with bids and offers directly.
"Ok," you might say, "liquidity is important, but surely we can just let the bots provide liquidity at night?" The problem is that markets are adversarial and bots can't really deal with "attacks" as well as humans (or at least the humans staking the money don't trust them to). There is all sorts of craziness that a market-making bot can't handle, and if you encourage people to rely exclusively on market-making bots then they can be taken advantage of (oh no, AAPL is down 50%, better sell, wtf, price shot right back up, rage).
It's safer and smarter to just have everyone agree on convenient blocks of time to crowd into the market. During those periods of time the market can be assumed liquid. The price abstraction works.
"But I'm a big boy and I want to live in the danger zone, let me trade at night!" Go right ahead. It's not only possible, it's readily available and people do it all the time. You can probably request some degree of after-hours trading from your brokerage right this minute. It's usually pretty easy -- usually you just have to ask for them to enable permission and promise that you know what a limit order is. Usually market orders are disabled, too, because they know that plenty of people would hit "accept," shoot themselves in the foot, and complain anyway :)
Bots wouldn't be required to provide liquidity during night hours. People living on the other side of the world will do just fine. We live in a global world now and people can buy stocks wherever using the internet, not just in the physical exchange like in the old days.
...and they can trade after hours just like anyone else who jumps through the minor hoops, yet crazy price action after hours is still an observational facts.
In liquid markets, "AAPL is $141.23" makes sense. It means that you can expect to buy and sell almost as much AAPL as you want at very close to that price because there are loads of buyers and sellers near that price. You can pretend that AAPL stocks have a price like a lamp at home depot: "I would like 2 AAPL please" is a safe thing to say.
In illiquid markets, "AAPL is $141.23" does not make sense. "I would like 2 AAPL please" is not safe at all. There are bids and offers, but not necessarily a lot of them, and not necessarily near each other. If you were to place the "2 AAPL please" order (or something related like "$500 of AAPL please"), you might find that you have purchased 1 AAPL for $141.23 and 1 AAPL for $299.57 because there was a big gap in the order book. The price abstraction completely breaks down and you have to "haggle" with bids and offers directly.
"Ok," you might say, "liquidity is important, but surely we can just let the bots provide liquidity at night?" The problem is that markets are adversarial and bots can't really deal with "attacks" as well as humans (or at least the humans staking the money don't trust them to). There is all sorts of craziness that a market-making bot can't handle, and if you encourage people to rely exclusively on market-making bots then they can be taken advantage of (oh no, AAPL is down 50%, better sell, wtf, price shot right back up, rage).
It's safer and smarter to just have everyone agree on convenient blocks of time to crowd into the market. During those periods of time the market can be assumed liquid. The price abstraction works.
"But I'm a big boy and I want to live in the danger zone, let me trade at night!" Go right ahead. It's not only possible, it's readily available and people do it all the time. You can probably request some degree of after-hours trading from your brokerage right this minute. It's usually pretty easy -- usually you just have to ask for them to enable permission and promise that you know what a limit order is. Usually market orders are disabled, too, because they know that plenty of people would hit "accept," shoot themselves in the foot, and complain anyway :)