Let's Encrypt has no competition because Let's Encrypt needs no competition: it works, it's cheap, and competitors can't really provide any advantages for its target audience (mostly people who just want a cert).
It is somewhat important for Let’s Encrypt to have competition: For reliability it is good to have alternatives with no shared infrastructure. If Let’s Encrypt ever becomes untrustworthy (and as a LE employee, I hope that never happens!) there must be alternatives so the root programs have the option to remove the Let’s Encrypt root. And there’s many geopolitical concerns too.
I love Let's Encrypt! Truly good work for the benefit of humanity.
Still. Everything needs competition. Any single organization amassing too much influence is always a bad thing, no matter how benevolent the organization.