All shares bought back are cancelled and thus it reduces the...

All shares bought back are cancelled and thus it reduces the total number of ordinary shares on issue.

It inherently increases the ratio of earnings per shares, as their are fewer shares on that side of the equation. So yes, it is helpful to holders because it makes each share they hold fundamentally more valuable on the basis of company earnings.

The value assigned to company shares in day-to-day trading is only loosely tied to EPS but over the long term increase your EPS and the SP will invariably follow. It is the opposite of diluting the value i.e. through issuing shares to for employee incentives etc.

The other benefit IMO is the signal that the company is sending to the market each and every time that they purchase shares, which is that the SP is fundamentally undervalued and that they are so confident in further growth that they see this as the best way to return value to shareholders. I also understand there are some more beneficial tax implications for holders returning value this way, when compared to dividends, but I'm not too familiar with that side of it.