[SmallDeadGuy]

It isn't, but the fact that you have two options (maintain yourself or switch to another solution) instead of a single option in the case of non-OSS (only switch to another solution) is a huge benefit. And, unless you're using some very obscure OSS or very outdated OSS (probably a bad idea), the likelihood is that there is a community around the product which consists of multiple maintainers/experts who are willing to continue development even after key maintainers move on