Of course, its because if some people are wearing the signature advertising some ICO, many people can see that there is a project like what are advertise by some signature program, so in that way signature campaign help many ICOs to be more popular to have many investors.
not only ico's but almost any projects or business that needs publications or exposure , signature campaign does really help them . promoting thru signature campaigns will also differ or varry its effectiveness depending on how popular the website or the forum that we are promoting . but in the case of bitcointalk forum , we are really sure that advertisers can always get the best possible result that they always been looking for because bitcointalk forum is the number one crypto forum , which means it can always appear in the pages of the internet or any other search engines .