No but you can interupt and LoS them easily. Find any sort of pillar of wall and eos/regen will outheal any form of damage a blm/smn can dish on you
BLM/SMN deal an extremely high amount of damage, SMN wielding one of the strongest burst in PvP. BLM being very close.

Right because getting good permanently reduce damage taken by 50%
You are implying the LB hits for 7.5k, and those surviving without Vit gear are magically reducing that number by 50%.

casters have casting time, can't attack while moving and cannot interupt when they are being interupted
Casters have insta-cast, which interrupt others' caster, can't be interrupted, and can be used while moving. SMN really only having to cast two spells with cast times (for damage) and having a pet that is pretty much full time damage that also interrupts.

I like how you are completely ignoring gap closer an[d] ranged attack which can be used to interupt casts/heals
Melees can't use gap closers while Bound/Slept, however they can while Heavied allowing them to get one gcd in before going back to getting kited. Also there gap closer isn't always warranted (Shoulder Tackle, Spineshatter Dive, potentially Overwhelm) because they have a stun tied to them, which can be bad when trying to avoid DR. Also, PLDs and WARs don't have gap closers.

The ranged attack melees do get are shorter than Ranges' attack range just so you know. And MNK's only ranged move is their PvP skill, Weapon Throw.