False. On nearly every boss in ToT there is a 1 shot-ish mechanic for a ranged player moving into melee range, some will only kill you, others will wipe your raid. You can time some of these mechanics with boss mods, but a very large portion of players do not use addons. If you would like a list of all the abilities that force ranged to stay at ranged per boss, you can either read the dungeon journal, or do some heroic raiding as ranged.
EDIT: Im bored.
Jin'rokh = Focused Lightning, raid wipe if you time it wrong while going into melee to drop your totem.
Horridon = Dire Call / Direhorn 1 shotting you if you are in melee when it goes out.
Council = Soul Fragment, raid wipe if you get caught getting targeted while dropping your totem in melee.
Megaera = Get targeted with Frost Beam while dropping your totem in melee-ish range = high chance of killing raid members.
Ji-kun = Caw.. dead melee, raid wipe.
Durumu = Life Drain in melee range = may be a wipe on progression, very hard to swap players efficiently in melee range.
Primo = Cluttering up melee, possibe to much splash damage depending on which abilites Primo has at the time.
Dark Animus = Extra font thrown at melees feet, who already have limited room to move.
Iron Qon = Arcing Lightning, raid wipe unless you outgear this significantly.
Twins = Ice Comet.. sorry melee i needed my totem down, dont care if i killed you all.
Lei Shen = Diffusion Chain, oops.
Ra-den = Oh, a fight where projection isnt a dps increase.