That's part of the advantage, yes (see post
153). The problem is that the use we get from the power roles needs to be significant enough that we're making it a dilemma for them.
To be more clear than I really wanted to be: With something like 2 Jailkeepers and 2 Trackers, scum are quite safe not fake claiming power role. At best, we get a bit of WIFOM action from the Jailkeepers (will the protect/block the Trackers/each other or not) and a small number of weak investigations (which are slightly improved by the three other claimed roles, but day 1 we're talking 1/19 vs. 1/16), but it's not much of an improvement over having 4 Named Townies outed and lined up for slaughter, which in turn is hardly an improvement over not having power roles at all (19% vs. 17% or something like that).
With other combinations of power roles, there's more synergy. For example, Hider/Tracker/Weak Doctor = Weak Doctor keeps Tracker alive, Tracker tracks Hider, and now we have a more effective investigation (either Hider hides with an innocent and we have someone else confirmed, or Hider hits scum and Tracker outs the scum the next day). And that's where we force the scumbags into doing something they don't like - either let that engine run, or fake claim and try to muck it up (which we would deal with on a case-by-case).
To summarize: The point of massclaim is to
try
to be proactive, but while we have the advantage of knowing the number of power roles, scum have the advantage of knowing what the power roles are, and depending on the power roles a massclaim may not be proactive at all, it may just out the power roles for little reason.
One of the things that occurred to me a couple days ago regarding the outed Hider part of the Troll plan: Roleblocker is bad (though apparently Troll is ok with risking a power role to that, now?), but so is Assassin - because while the Hider can hide from the Assassin... read the last part of the Assassin PM: "If a kill fails for some other reason, you do get to try it again." That means the Assassin can just keep targetting the Hider, until the scum get a double kill (either through the Assassin, or through killing the Hider's target, or through the Hider picking scum).
It may not be the most devestating plan ever, but it does counter the "at least if we out a Hider, the Hider can hide from the scumkill if we don't give them a Roleblocker" argument to some degree. So, my current thinking is that it would be a bad idea to give the scum an Assassin if we out any power roles, even a Hider. Which leaves Rolecop/Janitor... and Rolecop is still quite strong with three hidden power roles.
So, my next thought was: We combine the two claim plans. We mass-Hider-claim. If we have 2 Hider claims, we're golden. If we have 0 Hider claims, we stop (or perhaps move to a Weak Doctor claim, but probably not). If we have 1 Hider claim, we continue to a full massclaim - Rolecop/Janitor in play, and I think an outed Hider likes the massclaim anyway in some ways (though I need to think about that more; Hider/Vigilante = Vigilante reveals kill target, Hider avoids that target; Hider/Tracker/(Tracker or Weak Doctor) = see above, which doesn't work so well if we aren't sure on the kill count/if the Hider can be blocked).
Anyway, that's way longer than I expected it to be and more time than I intended to spend on it... I don't know that massclaim even makes the 1 Hider-claim case better, much less bumps the overall plan up enough to make a day 0 claim strategy reasonable, but I do think it's worth considering as a possible improvement to "give the scum a Roleblocker or Assassin and screw the claimed Hider over" or "give the scum Daycop/Janitor so as not to screw the claimed Hider over, even though it's a bad idea".