As many here know, I have coached youth sports for 25 years.
I have been on both ends of butt-whoopin's. (Fortunately I have had very good players so it wasn't me very often)
If I'm down big, I NEVER expect the other team to help keep my team close. That is our job.
If we are up big, I will try to keep the score down, but I will not tell my players not to play hard. At some point, your team needs to make the plays.
I also don't think any mercy rule should be invoked until later in the contest.
I have been leading 12-0 in the first inning of a 15 yr old league, and had parents/coaches from the other team angry because I didn't let up in the second inning.
That makes me mad.
Sports are competition, .. if you can't handle that, find something else to do.