Guru is a personality, who is a guide, and having a guide is definitely beneficial.
Offcourse, everyone is equal to god, but nevertheless, god is not same to everyone.
guru has higher understanding of Lord, and hence helps you attain your aims faster.
Also, one more important thing is , whether you want a guru or not, irrespective of that, you will find a guru allocated by time only, and even a wood log, which made you slip and fall two times, and modified to be more careful next time, acted as guru at that time isn't it.
So , you will find one, only if time wants you to. but it is also true that you will have one or the other guru guiding you at any and every point in time. Luckier are those, who are guided by supreme time himself, and luckiest are those, who are guided always by the supreme will.