I think this is always a bit of a silly argument. If Netflix was showing everything, but the tech was terrible, no one would've signed up. You need both.
If I was a little less honest, it would be easy to skip paying the subscription entirely. I generally use their apps now to find and try new shows, then download them to Plex once I know I like a show (so I'm not burning bandwidth fetching shows I'm not gonna watch).
The whole "are the normies capable of this" argument has turned into an arms-race against Youtube/FB for easy setup guides.
That said, yes, the number of people they'd loose over shitty interfaces is probably kinda small, but I'd argue that as guides, youtube vids, and even all-in-one seedboxes become more available, that population is gonna grow. All it takes is some streamer to lay out the current process.
I am willing to bet that this had zero impact on cable subscriptions.