While this may be true, it's not clear that they are the optimal way towards this end. We may be able to substitute more effective mental forces. See Will_Newsome's comment for an example.

Note that I speak, at Jeniffer's request, only of potential downsides. As great and even life changing as they may be for some, effects like these:

Once you have established some degree of concentration you should be able to "see through" thoughts and emotions without getting swept away by them.

After practicing for some time (hours, days, or months) you should be able to "see through"5 arising thoughts and emotions without getting "stuck to" them. Demanding thoughts and emotions will arise, and by "seeing through" them you maintain your observation of the breath as they continue (unattended to) in your peripheral awareness.

... are not for everyone. This kind of development of awareness can be seen as a rubicon. When you change the way you think you become a different person to that which you were. As the paper I mention describes, the changes are not universally beneficial. That's seldom how the world works, I'm afraid.