ok so let's break down the gist of that article.

Bitcoin Value is Partly Determined by Bitcoin Scarcity

Not all cryptocurrencies have a maximum supply like bitcoin but some do. Does that mean they are valuable?

What Gives Bitcoin Value? Difficult To Take, Yet Simple To Move

Well again, most cryptocurrencies rely upon public key cryptography for their security and such. So that makes them difficult to take if you don't know the private key but simple to move if you do know the private key. So that means all cryptocurrencies are then valuable?

Or is bitcoin somehow unique in that it has value while some of the others don't yet they function essentially equivalent to bitcoin. Maybe bitcoin is just treated as more valuable because it is more popular thus more people use it than some other cryptocurrency? Is that the basis underpinning bitcoin's true value proposition because if so, that could change. All it would take is people to start using some other cryptocurrency in place of bitcoin and then bitcoin would be less valuable?