I think the point is that with thin margins and capital costs, 1.6% (compounded over decades) could be a large chunk of your profit.
TFA discusses this:
> To justify their investment and make a profit, "it's very important for a developer to be able to project that the wind farm will produce a given amount of electricity for 25 or 30 years", the typical lifespan of a wind farm, he says. Even a relatively small, unexpected reduction in that energy output can upset this investment calculation and make the wind farm not financially viable, Finserås says.
If wakes losses have been known for years as asserted by the piece, I'd argue it's the fault of the operator and investors building a farm downwind (or potentially) of another. The only thing I can think of is if regulatory or zoning changes caused underlying assumptions of wake loss to change.
It's like setting up a low margin Italian restaurant with none nearby and a few months later another Italian restaurant sets up taking your revenue, tough luck then
TFA discusses this:
> To justify their investment and make a profit, "it's very important for a developer to be able to project that the wind farm will produce a given amount of electricity for 25 or 30 years", the typical lifespan of a wind farm, he says. Even a relatively small, unexpected reduction in that energy output can upset this investment calculation and make the wind farm not financially viable, Finserås says.