It would be too strong. Scythe is already a lock down item used to burst people, and it does that very well. Taking away passives which often gives survivability on top of that would make it extremely strong for that specific purpose.
Not to mention that if you buy Scythe to counter a hero’s passive, you also counter every other hero in the game because Scythe is already a really good item overall.
People really need to stop asking for these two items to combine.
Phylactery is already a massive early game power spike, it does not need an upgrade. And the heroes that already get phylactery certainly do not need to get extra cast range without having to commit a slot to it.