Seems more nuanced than that. Herd immunity is a function of how contagious you are, which with COVID is a function of how symptomatic you are, right? I think someone who's having coughing fits will more likely spread it. If the vaccine decreases symptoms, then it strengthens herd immunity.
Also, even if herd immunity is impossible, some reduced spread is a good thing by itself
Data from other countries with a >90% vaccinated rate for Covid would suggest otherwise. Take a look at Israel or Ireland in the past few months, for example. Israel is currently debating whether or not a 5th booster will be enough as they're seeing record infections.
But there are vaccines that are more than ~75% effective at preventing infection, which is the number that Fauci kept mentioning when this all started.
Herd immunity does not depend on the efficacy of the vaccine. It depends on the R_nought of the disease. There are several ways to reduce the R_nought below 1 (at which point we achieve herd immunity). Vaccines is just one of them.
Claiming things that vaccines don't work, doesn't prevent infection, impossible to achieve herd immunity with them- helps absolutely nobody.
Covid-19 vaccines don't prevent infection, and it is impossible to achieve herd immunity with them. These are facts, and they are relevant to the comment I was originally replying on.
Also, even if herd immunity is impossible, some reduced spread is a good thing by itself