no, buyback is not a new way to attract investors and there are already many examples of projects that do it that way but still cannot make a big demand in the market. ways like that can be done if the product has attracted a lot of people
but, I feel that it is quite influential. imagine, when you buy at ICO or pre ICO prices, and get a lot of bonuses under normal prices, and they intend to buy back, it will make investors interested. however, this only happens to projects that are truly trusted. it will increase the value and quality of the product, and the price of the token.
That case those who invested with the pre-ICO are safe with their money no matter what happen to the project as the buy back program basically makes them get their investment, I think the buy back program is also lower than the ICO price or those who offer a buy back program does not give a lot of bonuses to early investors or pre ICO investors as ordinary investors with a little investment will suffer when these big investors will dump.
you know if big investors sees a small percentage of profit, they will take that as that is short term and they will earn a significant amount since they invested a big amount of money. That's pretty it, they have to ensure that interest of all investors will be protected for the project to succeed.