Curious if anyone else has thought this. Heat wave, as a move, is just genuinely too good for what it offers when compared with other widely-available spread moves.
Some types don't get a viable spread move at all outside of signature moves (fighting, steel, ghost, flying)
Other types get spread moves in the form of utility moves.
(Dark with Snarl, Bug with Struggle Bug, Electric with Electroweb, Dragon with Breaking Swipe, Ice with Icy Wind)
And other types get spread moves that hit allies as well (Electric with Discharge/Parabolic Charge, Poison with Sludge Wave, grass Petal Blizard, ground with Earthquake/Bulldoze)
And finally, other types get spread moves, but they have specific requirements to become usable (Psychic with Expanding Force, Ice with Blizzard)
So when dealing with actual no- or low-drawback spread moves that are commonly learned, there aren't that many types that even get access to them. These include:
Fairy (Dazzling Gleam)
Normal (Hyper Voice)
Water (Muddy Water)
Rock (Rock Slide)
Fire and Water get honorable mention for access to Eruption and Water Spout being a bit more common, but the above four are really the only ones that have very wide distribution.
Normal is allowed to have more power in Hyper Voice because normal is objectively one of the worst attacking types in the game, with 0 super effectives, 2 resists, and 1 immunity. Normal is often allowed to break rules on move power (which is why it gets nasty things like Extreme Speed)
Rock slide straddles the line between utility move and damage, since 70 BP is pretty low, but the 30% flinch chance is huge.
But Heat Wave, on the other hand, is allowed an extremely high 95 BP even though it's got the low miss chance of 10%, as well as a 10% chance to burn, and it's not even on a terrible offensive type to make up for it--Fire isn't the best offensive type because two of its super effectives (bug and ice) are literally the worst two types in the game, but hitting steel for super effective is huge, and grass is likewise a strong type to give good damage into. And being resisted by rock isn't the worst thing in the world since it's likely in the #3 worst slot.
Muddy water and Dazzling Gleam are the closest comparative moves, and both are just far worse. Muddy water has 10 lower BP, while also having 5% higher chance to miss. The accuracy drops can be impactful, but burn is way more impactful since it persists on switch-out and guarantees its effect.
Dazzling gleam is perfectly accurate, but with 15 less BP it feels far more fair, especially since boosting fairy damage is harder than fire (since fire gets a +50% from the sun).
There's basically no other high-damage no-drawback spread move in the game that's got common distribution like heat wave. It feels strange that it's allowed to be so much better than the other options. Thought, admittedly, there's a lot of signature spread moves that make Heat Wave look tame, these also are tailored to just one pokemon.
