It depends, because traffic in reality can be:
a) quality traffic (your niche)
b) any traffic
In the case a) your site will benefit from it, as google will consider it as a definite plus. For example, if you have a travel website, and all the redirects come from other sites (domain names) related to the travel industry, then it's good.
In the case b) it can be good sometimes, if there are not too many non-related websites redirect to your website (it will boost your positions) but in most of the cases it will be bad for your site, as hundreds and thousands domains that have nothing to do with your website will be pointing to you, google will rather mark it as some sort of suspicious activity. Nothing good will come out of this as time goes by.
Also, even if you say sites are related to your business, nowadays Google doesn't pay much attention to it (compared to like 10 years ago). It's lots of other on-line optimisation: site structure, texts, keywords, social media etc.
Anyways, if your main concern is to get the good external SEO to your page, buy the program called MoneyRobot and forget about the manually adding links , buying extra domains, redirecting them and all these things.
(I am just a happy client using this prog in my business, without any other interest of advertising them or anybody else).