Digital scarcity is not a feature it can be the consequence of:
1) The usefulness of a service a DAC provides (compared to the usefulness of a service that uses a centralized ledger). The advantages over a centralized solution could be: Potentially cheaper fees (eg. lower rake with a gambling/poker service), anonymity, no corruption/transparent.
2) The network effect of one particular DAC (there may be many DACs providing a similar service). This network effect might in the first place be initiated by successful mass market marketing.
The Bitcoin blockchain (the unique longest valid chain starting with Satoshi's genesis block), had digital scarcity (by this, I mean a controllable quantity, with an unalterable limit of 21 million). Nothing like this had ever existed before without a centralized server, and this p2p scarcity existed before Bitcoin was useful (1) and even before it had an economic network at all, let alone network effects (2).
So I don't see how you can be right about those.
But saying other DACs are not legitimate because Bitcoin (or any other DAC) provides digital scarcity is wishful and moralized thinking.
How is it wishful or moralized? Its unambiguously pessimistic, and (I think) makes no reference to morality at all.
As for the morality aspect of it: That was a bit confusing. I should have said: If someone goes ahead and states that Bitcoin SHOULD be the only chain to provides the service "transfer of tokens" (which becomes the transfer of value because this service is perceived as (potentially) useful (in the future) and the Bitcoin tokens are necessary to use this service) because it was the first one out there. Then this statement is wishful thinking and a moral statement.
It is obvious that it is moral, see the word "should".
It is wishful thinking in case Bitcoin doesn't perform well in terms of paramter (1) and (2), see below.
Overall the statement isn't based on market forces (aka everyone does what is in his/her best interest). Instead of assuming Bitcoin defines "digital scarcity" I would propose to analyze the system based on the assumption that all individuals do what is in their best interest. I suggested that individuals are guided by two things when trying to maximize their interest here:
(1) Use the chain/DAC that has the best features/is most cost effective/is the most secure
(2) Use the chain/DAC that has the biggest network effect. More specifically: Use the DAC/chain that has the biggest volume (less price volatility), the chain/DAC that most merchants accept and so on.
had digital scarcity (by this, I mean a controllable quantity, with an unalterable limit of 21 million)
What your definition of digital scarcity refers to is relative: As a fact you can copy the code and release a new chain (and maybe change an few symbolic parameters; altcoins). The Problem is that this has no advantages (equal regarding efficiency/features, see (1) above) but only downsides (worse in terms of network effect, see (2)).
Therefore I think the two parameters above [(1) and (2)] are a better analytical tool to analyze whether the analyzed chain has the potential to create "perceived digital scarcity" than to assume that Bitcoin defines digital scarcity. I said "
perceived digital scarcity" because my definition of a network with valuable tokens (one could call this "digital scarcity") is relative to parameters (1) and (2). You can also say "digital scarcity" is a result of (1) and (2).
Would you agree that it makes sense to say that chain xy has "Digital Scarcity" insofar it performs well in terms of (1) and (2) - respectively will have dig. scarc. in the future when the market confirms that it performs well with respect to (1) and (2)?
P.S.: We can leave out the "SHOULD" and say "Bitcoin defines digital scarcity in terms of the service 'transfer of tokens'". Then, based on what was said above, the statement is misleading or potentially wrong and wishful thinking in case Bitcoin doesn't perform well in terms of (1) and (2).
PPS: The above referred to "digital scarcity" which for me implies comparing chains that all provide the same service and therefore dissolve "digital scarcity" if the word is understood in a traditional sense (= assumption that there can only be one DAC/chain to provide one type of a service which as a fact is not the case).
Now to evaluate whether a chain / DAC is to prefer over a centrally kept ledger those can be criteria:
Potentially cheaper fees (eg. lower rake with a gambling/poker service), anonymity, no corruption/transparent.
There are also disadvantages but that is another topic again...