I didn't say it was the only reason: I said I didn't buy it as a reason except as retroactive logic. Solars are the base because they were set as the base for 1ed(though supposedly Dragonblooded where originally going to be that until it was changed in development?), and it's basically stayed the same since.
Sure, but there's a difference between new viewers and new players. A player has to create a character, which means there is a larger amount of knowledge they'll need to get, especially for factions that have a more settled place in the world. And having a stronger narrative can also be a restriction if you don't want that narrative. So, this is something of a reason to favor Solars for new players as you say(though I think it's less than you think, and mostly ends up a wash as for which is better). However, this is not the case for a viewer: they're not going to decide on a character. They cannot chose any number of narratives to explore. They can only watch what you produce.
And, since you're going to have to introduce things anyways, the argument that you'd need to introduce the Silver Pact or the Houses is not less of a burden. Sure, there are things that are going to take some amount of introduction: Exalted's heaven, Hell, or underworld are all weird and would make somewhat poor first settings. But 'hey, the main characters are all noble scions from a great house, vying against other houses for the throne' isn't a setting detail that's super outside of what people can understand: look at Game of Thrones. Hell, that show/book even has the slow introduction to more elements as time goes on: the Frey's and Tyrell's are eventually pretty major players, but it's not like we know much about them early on. I'm pretty certain the Frey's aren't even mentioned until further into the show.
Basically, for any type of exalted you're going to have to introduce allies, enemies, the local area, the goals of the characters, and just setting elements. The names of all of these are going to change depending on what type of exalted you chose, but for a number they're sufficiently similar to things people know (and framed that way in setting, which is important) that there wouldn't be much confusion if you, say, had them be DB's doing house stuff.
Yeah, for live action Solars, possibly followed by Extingents, are probably the simplest while also not adding too many elements that need a lot of explanation like Sidereals(who actually do tend to have their own issues).
