Yes, bus is very important in all locations BUT very few purposefully design their rail network (or neighbourhoods) to require 90% of passengers to be bused into the station.
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Anyway, happy to be wrong. I'd love examples of numerous high frequency 20km long bus routes in mixed traffic feeding a single station that I can visit those locations. I've not stumbled across any in quite that situation. Stations in Jackson Heights (Queens) probably get the closest but NY is also unique in the world for having an almost completely stalled expansion for 80 years.
We're gonna get off-thread but the flaw in your argument -somehow trying to double down or otherwise justify the absurd, easy-to-see-with-the-naked-eye argument that Finch Station is somehow unsuccessful - is that you're looking at it in isolation. It's a terminal station with massive parking and bus traffic. The next 2 stations - NYCC and Sheppard, have neither. They function, all the stations, AS A UNIT.
Similarly, VMC has (or will have, when developed) no surface parking, though YRT will certainly feed in. But 407 is designed to take the car/bus traffic while VMC will be more walk-in based. Same goes for the planned Yonge extension: RHC will be for walk-ins (and bus/GO transfers) and Longbridge will be for cars. A subway SYSTEM can have both. And Finch's high ridership is not some illusion or flaw or spin. Oh, and it's also in a hydro corridor, which prevents the immediate density that would likely otherwise be there (and which is there to an extent, via the Xerox tower across the street).
You're also ignoring cause and effect. There are so many bus lines feeding in BECAUSE the subway doesn't go as far as it should. Development has continued far north of Steeles, which is why it makes complete sense (once capacity issues are addressed) to bring the subway further north. Development has also expanded (but at lower densities) to the east and west, particularly the latter, which is why an LRT there makes sense. There is nothing "natural" about Finch as a terminus; it's just where they stopped building. (This is also the massive logical failure the "just extend it to Steeles" crowd makes. It's completely un-natural and non-sensical; it's only where people pay their taxes to different organizations.)
Highway 7 is a more "natural" terminal given our current urban area and ,as I said above, once the Yonge line is extended, Finch's current function will diminish as the buses that now feed in are diverted to Cummer, Steeles and Highway 7. The parking function will remain, but also likely be diminished and so the ridership in the future is likely to be lower than it is now. And then you'll get more walk-ins, fewer buses making long treks on the road etc. etc.
So, resisting the urge to make a glib remark about how you can be happy to be wrong, I think you just need to situate the station in its proper context; as a regional terminal station located not-quite at the municipal border and, even less so, at an optimal location in relation to its end users, who are coming from the north, east and west because there is nowhere else for them to converge.
