Compared to a regular stateful password manager? Absolutely, for all the reasons mentioned by the parent poster. Stateful password managers are just more secure since the sitepasswords have no relationship between each other, so individual sites leaking a site password does not give them any possible attack.
Compared to using just the master password for all sites? Well, a stateless password manager is probably better than that at least.
Compared to what?
Compared to a regular stateful password manager? Absolutely, for all the reasons mentioned by the parent poster. Stateful password managers are just more secure since the sitepasswords have no relationship between each other, so individual sites leaking a site password does not give them any possible attack.
Compared to using just the master password for all sites? Well, a stateless password manager is probably better than that at least.