if the exhaust manifold pressures are so high that the wastegate is being forced open.. you've got a massive restriction that you'd wanna do something about
as you know a turbo makes boost 'virtually' exponentially, so the wastegate is a vent before the turbine wheel to relieve pressure to 'regulate' boost being made by the turbo, if you physically block (even partially) that 'vent hole' then it forces more air through the turbine wheel, if your already at the turbo's upper flow rate limits, then you can only imagine what stress this is putting on the turbo, not to mention unstable conditions like boost spiking, its not just the turbo that you have to worry about, excess boost, and air that cannot be exhausted will generate high exhaust manifold pressures, which generates high temps, which 'COULD' cause knock conditions and damage to rings, valves, manifolds etc