I’ve been using MacVim forever, and finally switched to using SublimeText with the vintage mode enabled. It’s scratching many of the itches I’ve had, but one of the main things I liked to do in vim was stuff like prepending content to multiple lines by selecting multiple lines and then typing:

:norm!Iprefix content

After a little digging, I found that you can add the following keybindings:

[
    { "keys": ["super+up"], "command": "select_lines", "args": {"forward": false} },
    { "keys": ["super+down"], "command": "select_lines", "args": {"forward": true} }
]

Now you can hit your command key and an up/down arrow to get multiple cursors, and then perform the insert to all the lines.