The attribution problem exists in both new and existing Marketo instances.
Despite all the effort to tag links properly and track ad campaigns, every single implementation falls short. Not because of lack of trying, but because today's systems do not solve this without heavy customization.
That is why ConversionPath was born.
Our team is so passionate about data driven decisions, we solved the problem ourselves because in some meetings, "our system doesn't track that" just isn't a viable answer. While technology and strategy have changed a lot in the last 4-5 years, something which hasn't changed is our solution to make multi-touch tracking easy and possible for everyone.