I think in the long run it would make sense for Bitcoin to inherently support transaction propagation privacy, without relying on external solutions. The more people use such a system, the better it can ensure privacy. High usage can only be ensured by making it part of Bitcoin.

Question is of course the practical relevance of tracking the (physical) source of a transaction. Currently most invasive measures from governmental bodies seem to take part via transaction analysis and following coins until they end up at an exchange or known merchant. However I wouldn't be surprised if the tracking of Bitcoin nodes became if a thing in the future (if that's not the case already).

Obviously the question is what trade-offs there are to be made, especially in terms of propagation times. At a first glance it doesn't seem to introduce any overhead to the blockchain though, as it seems to only affect transaction routing between nodes. Admittedly I have yet to take a closer look though.



If you are referring to LN -- to my understanding Dandelion would improve privacy on a different level. While LN makes transaction analysis much harder, Dandelion obscures the source of on-chain transactions (eg. opening and closing transactions when referring to LN) in terms of network topology (and by extension on a geographical level).