Author here. It was a lot, but seeing the number go down rapidly was a nice motivator. Keep in mind that these are just pre-made 1-word cards, so they're much faster than the full-sentence cards people suggest, which are likely more effective though also more time-consuming. Furthermore, French has an unexpectedly (for me) large number of cognates with English, so many of those words were freebies for me. If I was learning Mandarin, for example, 50 cards a day would require an absolutely enormous amount of effort, most of which would likely be wasted.
You are correct in that a decent chunk of the words are relatively useless, and I forgot many of them already after stopping Anki for a few months. There were also some words that I had no idea how to use, as you said. However, I did some extra looking-up of difficult words, and the deck included example sentences for many of the words. Also, I definitely claim that your method is more effective, but clearly this one at least worked well enough to do what I did.
I wrote an article[0] about my own method for language learning, focusing mainly on the spaced repetition aspect.
[0] https://mochi.cards/blog/using-spaced-repetition-to-learn-a-...