Without fully qualifying what “easier”, “good product”, and “good experience” mean as well as delineating project constraints such as time, business value, and life it’s not possible to truly have this discussion.

Even so, I am inclined to argue that in most cases the exact opposite is true. That is, it is actually “easier” to create a “good product” with a messy codebase, because in most cases “easier” and “good product” are understood by primary stakeholders to mean business value at this moment.