"the problem is that nobody else made an alternative that gained any kind of wide-scale adoption"
That may be because the faults of SysV init, while real, aren't as serious as some people assert. Yes, having something better is desirable, but outside of some edge cases (for which there are alternate init systems that can be used), it's not really that big of a deal.
Also, in my opinion, systemd is worse than SysV overall anyway. It does improve some things, but brings so much badness along with it that it's not a good tradeoff.