Yep, that's correct. The task killers try to mimic what the OS does natively, but not nearly as well. Killing the process has always been bad, in windows, in linux, in DOS.....and in Android. Lots of things are happening when an application shuts down properly, cutting those things off and killing the application is akin to using a broom handle through the spokes of your bicycle as a brake.
It stops the bike, but has "consequences"