Are electric scalp massagers relaxing or just another trend product?

My father suffers from partial alopecia that has been very frustrating to manage. We have tried a lot of treatment options to no avail. Electric scalp massagers have become popular in many spas and even for personal home use.

I came across an advert stating that electric scalp massagers are very relaxing and comfortable. There is also a widely accepted belief that it helps a great deal with improving scalp blood circulation,promoting hair growth and tension relief.

Is this just an advertisement line aiming to promote sales of these massagers or is it a scientifically proven fact?

Do they require any technical knowledge to be able to use them effectively? I am skeptical about them as a lot of trendy products these days tend to use health benefits to attract the vulnerable masses.

I have tried researching their prices online as well and honestly there isn't much. Few online vendors such as Alibaba appear to have stocked them in plenty. There are a lot of brands on display and I am wondering which ones are affordable and safer to use.