Like vo2max target power, the ramp test has some assumptions about aerobic fitness. If those assumptions are not true, then the ramp test will fail to give a reasonable estimate of FTP. Call it what you will.
When I’m reasonably aerobically fit, as measured by “ftp as % of 5-min power in last 90 days,” then ramp test gives reasonable results.
Above FTP, power targets depend on physiology and current fitness level. TrainerRoad’s vo2max 120% power targets assume “ftp is roughly 85% of 5-min power” (with 5-min power as proxy for pVO2max). If you are above that, say ftp is 90% pVO2max, then your vo2 workout target should be 111%. If you are below that, say 78% pVO2max, then your vo2 workout target power should be 128%.
In summary, I believe there is a range of aerobic fitness (as defined above) that results in “good” ramp test estimates. However even with a reasonable FTP esimtate, that may not give reasonable with vo2max and anaerobic power targets as explained above.