The confusion comes from people using "skill floor" for "learning curve" instead of "effectiveness".
But this is a thing where definitions have shifted over time. Like jealousy. People use "jealousy" when they really mean "envy", but correcting someone on it will usually just get you scorn and ridicule, because like I mentioned, language is fluid.
To put it simply, think assault rifle vs sniper rifle. Anyone can use the AR and spray and pray and do pretty okay. You can't do that with the sniper rifle. So the AR has a high skill floor (minimum effectiveness) whereas the sniper rifle has a low skill floor (low minimum effectiveness). But the AR has a low skill ceiling too a point where you can put in endless amounts of skill and see no improvement in effectiveness. The sniper being an infinite range OHKO can scale to the end given aim skill and map knowledge.
Another example would be Reinhardt in Overwatch. You can tell a noob to "look in that direction and deploy shield" and they will contribute to the team. You can't put a noob on Widowmaker and have them contribute (as) significantly.
"Skill floor" is another one. People generally interpret that one as "must be at least this tall to ride", but it actually means "amount of effort that translates to result". Something that has a high skill floor (if you write "high floor of skill" it makes more sense) means that with very little input you can gain a lot of result. Whereas a low skill floor means something behaves more linearly, where very little input only gains very little result.
Even though its just the antonym, "skill ceiling" is much more intuitive in that regard.