Yes this is an interesting topic because the familiar Help action seems like it can really be abused. (Disclaimer: This opinion has nothing to do with this campaign, it's players, or the Dungeon Master's rulings on how to use the familiar. It has much more to do with other games I've played.)
I'm in a game where every character but one has a familiar, and generally all characters get advantage on all things, barring perhaps a second or third attack in combat after gaining advantage on the first. It seems to get out of hand. I've told my players in the campaign I just started Dungeon Master'ing that they at least need to be able to role-play and justify how the familiar is helping. A bat likely can't help the barbarian lift a giant boulder, and a gerbil isn't likely to help influence a vendor to give you half price on that set of full plate you wanted.
I'd be curious to hear some of your thoughts on this as players and a Dungeon Master I enjoy playing with and who don't seem to try to abuse things at all, as it is quite pervasive in other games I've seen. Perhaps such things need to move to another thread, though?
As a Dungeon Master for many years, preventing abuse and min/maxing is a hazard of gaming and is your responsibility to control. The Help action rule is certainly a benefit, but I've always ruled that the Helper has to have either the skill involved or something complementary, in order for help to apply. A cloud of familiars distracting enemies is viable, but so is a Gust of Wind cast by the enemy totally reasonable to fling those familiars into a wall, doing 9 or so damage and *poof!*. Or any other AoE spell. In those cases, I've allowed the familiars that can be pulled into dimensional pockets get a chance to avoid the attack, if they've not used their Action that round, but that's about it. The odd one or two familiar/harasser might be ignored, but too many and the enemy sees the threat and reacts appropriately.
A familiar also has to be able to help in the skills area, too, anything without hands can't do fine manipulation, but you are right - justification is key. If they can't come up with a valid reason to gain Advantage, they don't get it. Some junior Dungeon Masters might allow full Help and not understand why combats and challenges are done too quickly. Monty Haul dungeons are never interesting to players that want to RP, just arcade-style gamers.
Edited: Gknightbc on 9th Nov, 2017 - 7:36pm
Yes, it can be. Then you can have invisible familiars such as quasits helping while invisible which makes them much harder to deal with. Cinder, the situations you mentioned sound abusive to me and are an example of min-max roll playing. If I was the Dungeon Master I would have the enemies make the familiars priority targets if such abuse occurred. That would stop that pretty quickly.
Edited: Kyrroeth on 9th Nov, 2017 - 7:38pm
Kyrroeth, luckily, that advantage only applies to Chain-Pact Warlock class, and even that is only good as long as there is no AoE that violates it's concentration and/or does serious damage. It's still only a sub-10 HP critter and easily killed. Something I've been curious about is why a pseudodragon, quasit or sprite form is still not an actual creature, when it gains magic resistance and such, and has all the advantages of being an embodied spirit. The Magic resistance alone is a huge benefit for a familiar, and is a great reason to always have it at your shoulder. The other benefit is that a Warlock's familiar can perform an attack, if the Warlock forgoes his own, unlike other classes familiars.
From what I've seen a limitation on familiars is that they don't scale well. At character level 20 they still have single digit hit points. They will have problems remaining undetected and will die very easily. I guess it comes down to how often the Dungeon Master will have them targeted.
Very true on all points Ky and Gk. My original Dungeons & Dragons group, the one I'm referring to, is definitely a bunch of min/maxers AND rules lawyers. We switched to one of the players as a 1st time Dungeon Master and he seems to be a slave to the rule book, under the watchful eye of the 3 other rules lawyers. If he can't find a rule to justify why he, as Dungeon Master, is making a ruling, he gets ripped apart. He thus, under those tenants, can't shut down the Help abuse. For the same reason he has had to allow the stealthy character to just walk out of a whole prison dungeon including walking right through a shield/phalanx wall of guards simply because the player kept rolling like 27 stealth. If the player rolled poorly he'd just run back around a corner, and re-stealth. Dungeon Master couldn't find a specific rule against this type of stuff, so had to allow it all.
These are big reasons why I enjoy playing with you all and why I started Dungeon Master'ing my own campaign with none of the same players.