Using a domain to redirect to another, the only benefit is for passing linkjuice to the redirected-to domain.
Say you have 10k backlinks to domain1 and you 301 redirect it to domain2. Domain2 will benefit from the 10k backlinks pointing to domain1.
This is good for blasting large blasts with scrapebox. Take a few old domains you don't use, or buy a few .info domains for cheap.. Blast them, so you don't risk your main domain, however all the juice is flowing to your main site. Keeps your main domain squeeky clean from blackhat and reduces the risk of getting sandboxed.
Many will argue, but yes the sandbox is real. Those who say it isn't, they just haven't been sandboxed before.