Alright, I'll say it one more time. Fox dthrow isn't D-tier. How is bowser Jr dthrow, which does the same amount of damage and has no sort of combo or follow up that even remotely works, an entire tier higher? It also doesn't kill until 200% at the ledge, which is probably uthrow kill range anyway. People say "just DI away and use a fast attack or jump" on fox dthrow. But if you DI down/away, fox can true combo dash attack or even usmash. With good timing, some characters can be very reliably frame trapped by dthrow to bair. Also, there are percent ranges where you can actually true combo an RAR bair even with perfect DI, which, even if it isn't attainable all the time, proves that frame traps out of dthrow are legit, and lead directly into utilt juggles. Sure, if they have a really fast fair with decent range they can probably escape a good chunk of the time, but you can bait this out and cover their landing after they whiff, which is a favorable spot for fox. Also, it's worth mentioning that if the opponent doesn't DI or DI's in, fox gets ridiculous true follow ups, including uair. You can bait this out by using fthrow at the ledge, then combo a uair for the kill.
The throw itself might not be that great, and I can see if you are arguing that most of the work comes from fox rather than his dthrow data, but this throw puts the opponent in a great spot for fox to rack up damage, and even if you whiff a bair, dthrow has a nasty angle for setting up frame traps, or covering their landing if they jump, which fox is amazing at doing. This throw is likely better than half the dthrow's in C tier.
Regarding fox bthrow, this throw is absolute trash. It only does 8%, has no combos, tech chases, traps or anything because of the horrid endlag, It doesn't kill at meaningful percents, and it doesn't even have a low enough angle to be good at forcing low-ish recoveries. This throw literally does nothing well, except doing decent damage. This throw is likely a bottom 5 bthrow, and should be in the lowest tier.