evilbob
Adventurer
In nearly every location on the map, the party can meet up with one or more NPCs that want to come with them. This is in addition to the "special" NPC chosen by the cards that definitely comes with them, and Ireena, who no good-aligned, sane party would let out of their sight. There are groups of children that need rescuing (some of whom can't be returned to anyone), good NPCs and evil NPCs that connect to other NPCs in other areas and need transportation / rescue / etc. You could easily end up with a small mob of followers, some of whom want to kill you and some of whom you need to save for major plot reasons. And nearly everyone except the children are potential combatants - "XP sinkholes" you might call them. 
(All the more reason to use milestones!) But even if they aren't sucking up your XP, they're still taking turns in combat and generally slowing things down. You can get players to play them in addition to their characters but that doesn't speed things up too much. (They do make excellent backup characters, though.)
How are DMs thinking of handling all this? I know my group is highly suspicious of the fortunes of anyone left "off stage" - Ireena in particular has been expressly targeted by Strahd and only the party is stopping him from taking her. Most other characters are likely to be quickly killed by either Strahd or their surroundings. But keeping a group of NPCs around is equally dangerous: they can be attacked or fall into traps or be killed by any number of area effects. So what do you do?
You could create some sort of safe house where you dump most of the NPCs; you ward it and protect it as best you can, although nothing is completely safe from Strahd and this doesn't seem like a plan that would work long-term. Plus you have some NPCs that are actually evil and you don't want foxes in your hen house.
You can drag everyone with you but they'll surely have opinions on things and pull the party in different directions. And combat slows to a crawl - or else they run off and hide, which just means they're off-stage again and easier to kidnap.
What are some better options?
(All the more reason to use milestones!) But even if they aren't sucking up your XP, they're still taking turns in combat and generally slowing things down. You can get players to play them in addition to their characters but that doesn't speed things up too much. (They do make excellent backup characters, though.)How are DMs thinking of handling all this? I know my group is highly suspicious of the fortunes of anyone left "off stage" - Ireena in particular has been expressly targeted by Strahd and only the party is stopping him from taking her. Most other characters are likely to be quickly killed by either Strahd or their surroundings. But keeping a group of NPCs around is equally dangerous: they can be attacked or fall into traps or be killed by any number of area effects. So what do you do?
You could create some sort of safe house where you dump most of the NPCs; you ward it and protect it as best you can, although nothing is completely safe from Strahd and this doesn't seem like a plan that would work long-term. Plus you have some NPCs that are actually evil and you don't want foxes in your hen house.
You can drag everyone with you but they'll surely have opinions on things and pull the party in different directions. And combat slows to a crawl - or else they run off and hide, which just means they're off-stage again and easier to kidnap.
What are some better options?
