So my Guide background gives me Survival skill proficiency (prof bonus for Wis(Survival) rolls), and navigator's tools proficiency (prof bonus for Wis(Survival) rolls to avoid becoming lost). And we've been told that you can't add prof bonus twice, ever. So.... why? Almost every background has a similar skill/ tool pairing. It seems tools are only useful for people without skills, and skills mean you never need to use tools.