I'm not sure what company you're at but there is certainly not a multi-year project in any I've worked at. There are long term _product_ roadmaps but in order to stay agile you never commit to something as big as a multi-year project. There are only individual features that get committed to. Even in core infra (heavily technical) where needs and solutions are known committed work goes out a year tops.
Absolutely you want people who delivered things from start to finish but I've never heard of those things taking multiple years. If it takes 2-3 years for your product to go to market it's a failure, regardless of whether it's an external or internal product.