I think there are other factor's beside the battery and EV's being dumped in the market that may affect the resale value that are not mentioned in the article.

First of all I believe that the car manufactures (especially for electric cars) these days use planned obsolescence tactics to limit a car's lifespan at one side, while also promising the buyers that the car could last for far longer compared to their old ICE cars. However this promise often doesn't seem to hold up in the real world which will decrease confidence once the cars start breaking earlier. This is especially problematic when you are running an business calculating in the promised lifespan instead of the actual lifespan, once a business finds out (and does the math) often it will make economical sense to dump the fleet.

On top of that I think a big problem with certain cars on the second hand market is big onetime investments. You can see that already in certain internal combustion engine cars that are know to require a costly fix after x amount of miles. This is quite important in the second hand market since you often have to expect to do the "big maintenance" once you purchase a second hand vehicle as people like to sell slightly before this maintenance is due (and often not tell you).

Where EV's may run for a long time without problems they require costly repairs once they do break. Most EV's are build in a mostly non repairable way, like many modern vehicles, and you have to pray that the parts will be available after 10 years. Also a lot of maintenance on EV's can not easily be done by an enthusiast in a shed as it requires special equipment, certification and skills. Where with an ICE engine you may run into smaller maintenance earlier you are paying these fixes incrementally, and may be able to do a lot of the maintenance yourself.

On top of that I think there is a certain saturation in the electric car market where people that care about buying an EV increasingly have a EV and the people that don't care (or prefer ICE) don't want to invest the additional premium, or uncertainty to buy an EV. For example I don't buy an EV because it's very impractical to charge it where I live and I like the added flexibility (miles) that an economy ICE car can provide.