The Enclose and Fill Tool Proposal for what I understood is not really the same functionality than one asked here.
It’s the morning now and I’m not so lazy anymore, then I searched in the forum 
I was more thinking about this post:
https://krita-artists.org/t/very-important-for-animation-filling-gaps/20895/15?u=grum999
But it’s not exactly a “filling gap” functionality.
What I see is the https://krita-artists.org/t/very-important-for-animation-filling-gaps/20895?u=grum999 topic was already opened by @Turbinskiy: it doesn’t deserve anyone to open and re-open the same subjects again and again… Why just not continue to talk on the topic already created?
Also, you don’t need to highlight this in an aggressive way:
You probably already now that Krita’s team is a small teams with few resources.
And as if a functionnality seems basic and fundamental from a user point of view, from a developer point of view it could be complex to implement… (and also fixing bugs might be more important than implementing new things, especially during beta tests phase)
Grum999