Yes, not a bad one either.
But "alternative" malloc implementations need people to actively decide to use them, which is reactive to some specific problem.
phkmalloc, by being OS default, meant the 10K+ ports collection got exposed to it.
I remember only one or two "Bah!, FreeBSD is broken watch me not care!" upstream reactions, everybody else went "Ohh, I guess everybody but FreeBSD are unsafe!" and fixed the reported bugs.
Some even said thanks :-)