John Mueller from Google stated in a Webmaster video that redirection of all URLs to the home page happens to be a bad practice. What you should do instead, is redirect the URLs one by one to a right new location.
You can think it is common sense to any SEO but it is seen that many sites go for a redesign and new CMS. They will then simply redirect the old URLs to the home page and not go for redirecting those URLs to new URL having the same content like the old URL.
John mentioned it in the video that redirection of everything on the homepage is bad practice as Google loses all the signals related to the old content in case you are simply stating that well, the homepage is going to the replacement of all the lower level pages.
You will end up confusing Google and it says it never makes sense in redirecting all the signals to the home page. John states that you need to avoid this bad technique.