If it is all that you have, then sure. But it is far from ideal and is not recommended (when other options are feasible) for good reason.
Well can't that same mentality be used with a ruger 10-22 that has 2 30 round magazines taped together?
That same mentality is not as "cut and paste" as you are trying to make it. Comparing 30 rounds of .22 is not the same as 17 rounds of 9mm. The 9mm has considerably more energy than the .22, and the energy difference between the 9mm and .45 ACP is much less than from a .22 to a 9mm.
If you have experience trap shooting, do you have a shotgun? I would rather have a shotgun to use for HD than any .22 lr caliber firearm.
**What is your definition of "point shooting"? I don't think you are using it in the same way that most do... At least, I hope you aren't since you are referencing point shooting in a defensive scenario.