Is this from experience, or from theory?
Seriously, a 4e GM can look at any standard monster for the level in question, can trivially know that no PC will have more hit points than that, and see that (in this instance) 150 hp will kill all the PCs. A GM who imagines that the PCs at a given level will have as many hit points as a solo of that level understands so little of the game's mechanics that it's a more basic mistake than putting a wight up against 1st level PCs in classic D&D and then being surprised when they don't have enough silver arrows and depth of levels to lose in order not to be killed by it.
From experience and in theory...
Ok, first there are 2 ways to die in 4e... the first is by failing 3 death saves and the second is by having your hit points reduced to negative your PC's bloodied level. So in order to survive the attack in the OP that was thrown at them a PC needed over 100 hit points at 13th level. Since 101 + would not allow an instant kill on a PC... are you saying that it's impossible for level 13 characters to have 101+ hit points? I know for a fact it's not...
Emphasis 1... This is not true at all. There are PC builds that have more hit points than some standard monsters of their particular level. According to the MM3 on a business card, a level 13 standfard monster can have anywhere from 99hp's (lurker) to 156 hp's(brute)... that's a pretty significant difference, and I have seen level 13 characters with over 99 hp's. The difference in PC hit points depending on the selections made for race/feats/role/etc. can vary quite a bit between individual PC's of the same level. Just as an aside here's a level 10 character that could have survived that attack...
[sblock]====== Created Using Wizards of the Coast D&DI Character Builder ======
Wardenforged, level 10
Warforged, Warden
Guardian Might: Earthstrength
FINAL ABILITY SCORES
Str 16, Con 22, Dex 11, Int 8, Wis 12, Cha 10.
STARTING ABILITY SCORES
Str 14, Con 18, Dex 11, Int 8, Wis 10, Cha 10.
AC: 28 Fort: 25 Reflex: 20 Will: 21
HP:
107 Surges: 17 Surge Value: 26
TRAINED SKILLS
Nature +11, Intimidate +12, Athletics +10, Endurance +15
UNTRAINED SKILLS
Acrobatics +2, Arcana +4, Bluff +5, Diplomacy +5, Dungeoneering +6, Heal +6, History +4, Insight +6, Perception +6, Religion +4, Stealth +2, Streetwise +5, Thievery +2
FEATS
Level 1: Toughness
Level 2: Improved Warforged Resolve
Level 4: Component Modification
Level 6: Durable
Level 8: Crushing Earthstrength
Level 10: Improved Initiative
POWERS
Warden at-will 1: Strength of Stone
Warden at-will 1: Earth Shield Strike
Warden encounter 1: Thunder Ram Assault
Warden daily 1: Form of the Fearsome Ram
Warden utility 2: Triumphant Vigor
Warden encounter 3: Earthgrasp Strike
Warden daily 5: Storm Strike
Warden utility 6: Bear's Endurance
Warden encounter 7: Earth Gift
Warden daily 9: Form of the Stone Sentinel
Warden utility 10: Returning Strength
ITEMS
Adventurer's Kit, Heavy Shield, Warsoul Longsword +2, Shoulderbow Hand Crossbow +2, Lifeblood Hide Armor +2, Amulet of Protection +3, Delver's Light (heroic tier)
====== Created Using Wizards of the Coast D&DI Character Builder ======
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Emphasis 2: Who said this? A solo at level 13 has anywhere from 396 hit points to 624 hit points... again according to the MM3 on a business card. So either this is hyperbole or a strawman since 150 falls nowhere near this range.
In other words no... it's not as simple or straightforward, with the numerous ways a player can increase and modify his stats in 4e, as you seem to be trying to make it out to be... especially if the DM doesn't want to be constrained to the guidelines presented in the 4e books.