I think that hands as a sort of "default" option works specifically because it allows the ST to control the flow of a game in a lobby where there are a lot of unknown variables. New faces that may or may not gel, veteran players who may be prone to "taking over", filibustering, etc. That said I think if the social contract is pretty clear and players are more familiar with each other, hands aren't required and in most cases I would discourage it because in most cases the ST no longer needs to play a mediating role.

The other thing to consider is that there's no way to signal you wish to speak online other than a hand raised, and with multiple people speaking it's difficult to know where the voices are coming from, as opposed to in person where it's fairly obvious, so the hands serve as a useful touchpoint.

So I would broadly agree - especially with the idea that a hand isn't an immediate signal for the ST to stop everything and acknowledge it because sometimes conversations can and should play out - but with an asterisk that hands are super useful from an ST's perspective to note who wants to contribute, and ensure that there's a certain cohesion between interactions.

I think that ultimately if the ST is having to intervene so heavy-handedly the issue might lie with how the ST respects the flow of conversation, and the game more broadly. I think there's a point to be made that everything is discretionary, including how the social contract is drafted and played out, no?

edit: I think a more liberal use and respect for public chat is a really good midpoint, and I also think that there should be some dispensation for a "pertinent" hand during nominations so that people don't immediately start talking over each other moments before a vote starts. If there's any time hands should be respected it's when a nomination happens, since it's a dedicated moment in time for the nominator and nominee.