All procedures are carried out after a clinical assessment of risk vs benefit. As mentioned above there is always a risk to any invasive procedure and angioplasties on minor vessels just do not justify a patient undergoing the risk of an coronary angioplasty as some of the risk, though of low frequency, if they do occur can be significantly life altering.
And while treating a severe narrowing in an important vessel has a favourable prognostic benefit (ie prolongs life but this is a hidden benefit) the same does not pply to smaller vessels.
As to the second part of the query, nope - a good house cleaning as such seen on “youtube” videos is not a good idea as if indeed a complication occurs this can vary from life altering to life threatening.
A better option is to undertake the boring but effective method of lifestyle changes such as exercising regularly, eating a healthy diet, sleep well and stopping smoking.