Can someone explain to me why I'd EVER want Sunfire over Deadmans?

- 2750 total cost. (Giants Belt + Chainmail Build Path)
- 600 HP, 50 Armor.
- Passive that grants movement speed, bonus damage on next auto and increased damage/slow if you attack with max stacks.

- 2600 total cost (Bami's Cinder + Chainmail Build Path)
- 450 HP, 45 Armor
- Passive burn effect that slightly scales with level (25 + 1x Level, Maximum of 43 damage) at 400 range.
For 150 gold, you're getting an extra 150 HP, an extra 5 armor and a massively more beneficial active that rolls damage, slow and movement speed all into one. Yes, Sunfire was in a bad spot before but Deadman's is the final nail in the coffin. Even champions who prefer sunfire for it's AoE damage could easily just get something like titanic hydra if they want splitpush power.
Sunfire either needs a buff or to just be removed. Maybe change the buildpath. As it is now, this item is hilariously outclassed by Deadman's.
.
's aura effect as that? I don't know.
, fire
or other fire-y champs and getting it for thematic reasons?