Yes, it increases oil pressure from stock, UNTIL the engine reaches about 70PSI max. Would you like a video? I have the big block high pressure spring in my slant six pump and it sits at 70 PSI idle oil pressure, where before it was about 30. I can rev the engine and it "might" get 74 or 75, but the relief valve opens "around" 70 give or take. It's even talked about in the MP engine book how it works. You are correct that it does increase the PSI at which the relief valve opens, but it most certainly does and will increase oil pressure at every rpm all the way to "around" 70PSI unless the oil pressure is already that high with the stock pump and in that case you wouldn't need the high pressure spring. You can disagree till the cows come home, but that doesn't make you right.
