If it fails, what protects us? Asserting that a travel duration of two weeks is the direct cause of a low season stay, or that it intrinsically defines it, is an excessive simplification.
Duration is a possible consequence of budget constraints, but not the mechanism that defines seasonality.
The low season is rather determined by tourist influx and overall prices, independently of the length of our stay.
For example, two-week trips during Japan's Golden Week are very costly, proving that duration alone does not impose the season.
This link should be treated as conditional rather than decisive.