Do you consider yourself accountable for pipeline, business performance and how do you keep sales accountable for proposing the pipeline well.

I do not consider PMM accountable for pipeline, no. We certainly influence overarching business performance (everyone on staff does whether directly or indirectly) but to me: marketing (traditional demand gen/content) builds the pipeline along with an outbound motion from sales. From there, PMM can influence velocity of customer journey stages via nurture campaigns, but ultimately sales/revops is responsible for actively forecasting, weighting, and reporting on pipeline.

Because I am not accountable for pipeline, I don't have a defensible answer to how I keep sales folks honest in how they weight/forecast pipeline. However RevOps does this very well (here) and there are tons of tools to help sales folks get this right more often than they get it wrong! Clari for example...6sense...definitely would recommend a peek at those tools to help get alignment on pipe gen/performance