You seem to be mistaking volcano on battle.net as being some substitute for a mindblast / trap combo.
That is not how it works in this duel.

Instead a Shaman uses volcano as a sort of interruption to lead into a grizzly strike. You volcano them, which stops their teleport for a split second, and then you grizzly strike them, and then you both teleport away. It is very rare to pin a decent character down with volcano, instead it is used both as targeted damage and interruption. On its own, it is hard to land more than 2 hits from the same volcano, whereas when a grizzly knockbacks someone while they are on top of it, it furthers the buttrape.

My personal best way of thinking of it, is as a wedge. A traplock is a cage, shutting down your opponent completely until they WSG out like a madman. A volcano, on the other hand, is a wedge. You shove it inbetween yourself and the opponent in order to force an opening for the attack, wedging yourself in there. Traps might be a padlock on the door, whereas the volcano simply shoves its foot inbetween them to stop it closing.

no, just about 30 lifers or so, it is easy to get over 3k life
talking about vitanec here, with block some of the good necs MIGHT(most shouldnt) get fhrd, however they will have the block delay to help them get away

no, I'm not, since not even that's a deathlock now that people are actually good at wsg'ing.

and does it really matter about the bear kb'ing them back into the volcano when they could probably just wsg out of it right after?

there are vita/dr necros? O_o

I thought they only came in either vita/no-block *or* mb/dr, not a bastard offspring off the two.
Yeah block necros just barely eke out above 2700 iirc, which is just above the threshold, but thats with perfect gear. A non-block necro won't get fhr, but he'll get utterly eaten alive by volc/bear combos anyway

Yes. Its the difference between getting hit twice, and getting hit 4-5 times.
Their greatest opportunity to escape from volcano is right after the first hit, as the FBR is on its timer.

If your bear strikes them, its not uncommon to land not just 5+ volcano hits, but a double or more bear-combo.
I've seen beefy necros go from full to dead in no time at all thanks to captain grizzly and his 12 inch dong

you can only lock for 4-5 hits? I can't ever imagine how necromancers are "medium", then, considering a golem can take a hit and a nec can wsg spear you then run off to re-cast bone armour right after.

Because fissure also persecutes them, and you both have equal tools to throw at each other; neither of you are good at killing each other, its an even duel.
If you break through a necro's armor and slap him twice with a grizzly, the duel is already over.

A duel against a bone necro is very difficult for you, but it is also very difficult for him. 'Medium' is not a matter of skill requirement but rather advantage.

Match-up discussions are never a discussion of skill requirement, a figure of 6:4 would mean that one would win 6 matches out of 10 vs someone of equal skill.

and, correct me if I'm wrong, but I'd consider spear a good spell to kill a druid with 3.5k life

I'm not sure if you understand.
Its not a question of individual player skill levels, but rather how challenging the matchup is in itself. A desyncing hammerdin is a much easier character to play than to play against; you must have good guessing skills and awareness as to where they are, and know how to properly walk south/dodge/etc, tactics which take good motor reflexes sometimes. Meanwhile, the hammerdin simply charges randomly and spams hammers, which takes 2 brain cells. Another example is a Blizzard sorc. A bad one can simply spam randomly blizzs all over the place and pray you run into one by accident, but in order to defeat her, you're going to need to play extremely well by both dodging blizzards and setting up and opportunity to land the volc/bear combo while she is on cooldown without flying into your eminent death. Equally skilled, pretty much any character beats the hammerdin, and a shaman has a fair matchup against a blizz sorc. That is the difference between merely counting the win ratio of equally skilled players, versus the amount of skill and effort they need to put into the duel. There are many characters on a Shaman that you need to player very well against to beat, but when you play well, you'll be in a strong advantage over them.

Hence, Shaman vs Bone Necro is a very challenging, fast paced and difficult duel. Yet so is Bone Necro vs Shaman, so its both party's duel to win.

Yes, i have 1 myself. Max dr, 75 res, 125 fcr, 86 fhr but no mb.