I may be wrong (it happens, occasionally!), but I think that 'kansetzu waza' means 'breaking techniques', not 'submission holds'.
'Tapping' an opponent to secure victory is only for sport combat, or an 'honourable challenge' (how many of the latter do you see, nowadays?!).
You cannot trust someone who has criminal assaulted or threatened you to 'honour' their apparent submission, once you let them go.

In self defence, a joint lock could be as part of a takedown or throw, or to damage/break the limb.
Choosing the third option; to hold/secure/restrain the opponent, is really dependant on circumstances, and tactical needs and considerations (it can be very risky).

Kansetsu waza
https://www.youtube.com/watch?v=ge34hs-4PKk
https://www.youtube.com/watch?v=otSAWYs7Qtw
https://www.youtube.com/watch?v=WMPllsGLisI