Lanefan
Victoria Rules
It mandates much more than that: it mandates against individual PC actions and in so doing negating some otherwise-reasonable in-fiction things the characters might do:Torchbearer has a rule that all the PCs have to enter and leave a phase (town, adventure, camp) together, and so in that sense it mandates a party.
"Most of us are wanted in this town 'cause of the last time we were here but Joe, you're not; so what say you ride ahead, scout the place out, get a big room at the inn, and then we'll try to sneak in and join you there?" (entering town at different times or maybe only one PC gets in)
"Guys, I'm going to be three more days or so finishing my spell research. I know time is tight, so why don't you go on ahead and get started on the mission; leave me trail-marks and signs and I'll catch up to you when I can." (both leaving town and starting an adventure at different times)
"We'll split up today. Bjarnni and Edweard will go ahead and forage, the rest of us will stay here and try our luck at fishing until noon or so, then meet them up on that ridge <points at map> before sunset." (leaving camp at different times)
The rule denies the players the agency to do any of these things.
And yet they can't follow those goals as individuals, they are mandated by rule to haul the party around with them...which (perhaps intentionally) plays hell with PCs having goals that directly conflict with each other or having goals that are not supposed to be party knowledge.But it doesn't mandate a party goal. The players have individual goals.
Sorry, but while I can get behind a soft-shoe player-side suggestion of "keep the party together", mandating it as a hard rule is IMO a fairly big step too far.