I don't think this is true. AMD never had an overall performance lead over Intel until Zen 3 and they sold fine even when they were further behind.
If Zen3D didn't happen at all I don't think AMD would be any worse off if they had nothing new until Zen 4.
Are people really going to make a new build with Zen 3D on a platform that's got to future beyond that as opposed to going with Intel when you can get in at the start of one? AMD fans would hold out for Zen 4 anyways especially with the GPU market still being the way it is.
I am the wrong guy to be asking that question. I bought a rog Strix B450-F for $90 simply for the ability to upgrade my PC to Zen 3. I bought a 32GB kit of E-die for $104 last year on Amazon. I had two 16GB hynix kits that I was running in one PC. Put in the E-die in the B450-F and it runs 16-19-16-16 timings @ 3800ghz completely stable. My B350 was never stable with memory over 3600mhz. I bought the Hynix gold P31 NVMe (1.3 gen) 1tb drive, couldn't justify the price of B550 boards considering Zen 4 will be AM5. The BeQuiet case was $80. I had a new Cooler Master 240MM AIO RGB sitting in the shelf.
My old P400 Phanteks case and AIO 240mm now run with the old 3600mhz 16GB kit and my B350 and the original R3 1200 quad core Ryzen CPU. When I get a Zen 3 CPU, this R5 3600 goes into the old build. I bought replacement fans for my GTX 970 for $11. The card runs like new again. Almost forgot I got a 550w evga GA gold power supply for $40 within the last year. So I had a lot of new components sitting on the shelf.
So basically I spent $170 + tax for a second system plus whatever the Zen 3D chip costs. I know a lot of people here use their systems for crypto mining or trying to find cures for cancer or folding teams. Zen 3 overcomes the memory latency issues that plagued Zen 2 and previous Zen CPU's. The Zen 3D talks of 15% gaming improvement. So from a Ryzen 3600 to a Zen 3 is 20% better gaming performance plus 15% for Zen 3D which should be good for 35% better gaming performance over Zen 2 for gaming.
I will keep the Zen 3D CPU for two or three years. At that point the DDR5 prices should be lower. The BeQuiet 500DX is pretty great considering it comes with 3x 140mm fans and can handle 280mm AIO's on the top of the case and 360mm in front. This is the 1st case that I bought that I could see reusing for a new build.