Yea that was just bonkers, that specific transaction was a specially crafted one using non standard mixing. If he had used default mixing settings he would have been unable to deanonymize the tx. At best it's comparable to when Monero allowed 0-mixin transactions.
Privacy must be by default, or it is not by definition private at all. If some transactions are private, some not - the 'private' coin transactions are compromised. Optional privacy compromises fungibility, too. If some coins are private, some coins are not, then coins are tainted and may be treated differently
Yes (in theory) Monero initially was as per Dash is still - but Monero is light years ahead of that now. Evan et al don't seem concerned, or maybe just cannot keep up - it's hard to tell.
However, privacy is becoming more of an issue, and may for some be a matter of life and death.
The difference is stance between Dash and Monero is clear. Dash cannot hope to be even 'one' of the leading privacy coins and is going in a different direction with its central marketing efforts. No one who knows what they are doing would even consider Dash for privacy when it really matters.
Lastly - privacy? Dash has a 'rich list' FFS!
https://bitinfocharts.com/top-100-richest-dash-addresses.html Show me Monero's?