Analysis of patterns could be very informative - but I've seen DABlinks which had been added by admins and >10-year veterans, so it isn't a straightforward problem. WP:TESTLINK is more a pious hope than a guideline.

I've changed my mind. I can see this being potentially very useful. In [https://en.wikipedia.org/w/index.php?title=Iota_Phi_Theta&action=history this simple case] from today, I reverted a repeatedly-edited vanity post, and "Disambiguation links" made the relevant edits stand out. In other cases, where a DABlink-adding edit has been buried under more recent ones, this could make it more easy to identify. (I haven't yet looked outside enwiki.)

I'd say very likely all, rather than nearly all. Most of my edits outside enwiki (32 languages) have been error-fixing. (I hardly ever look outside home languages; links elsewhere might be guesswork, and will need confirmation.) If this benefits any non-English WP - excellent, the effect won't be limited to there.

@Samwilson - dablinks is only added if (I Ithink) there are 7+ links in an article. User:DPL bot sends 'nastygrams' to registered users who add even one DABlink (see e.g. [https://en.wikipedia.org/w/index.php?title=User_talk:Narky_Blert&diff=1035020962&oldid=1034126318 for one of my mistakes]) It doesn't bother with IPs, because they don't know what talk pages are. The list of all current DABlinks is maintained in [https://dplbot.toolforge.org/disambig_links.php?limit=500 Disambiguation Pages with Links], updated twice-daily.

This appears to duplicate what User:DPL bot has been doing in enwiki since 2011.