You're not wrong and neither was anyone else. But more lumens are only one piece of the puzzle. Upgrading to a light that has 300 additional lumens is not going to benefit if those lumens are wasted as flood, as the lux at distance will be the same or less than the prior light with X-300 lumens. Basically if you upgrade just lumens it's possible all that's happening is a wider area is now being illuminated but since washout is due to another light source overriding the luminous flux of your light source a more concentrated beam is needed. If the OPs current light is distance measured as 50m to 0.25 lux and his next light is 300 lumens brighter but has the same 50m to 0.25 lux all he's done is increase the ouput and increased the candela measurement but not done anything to overpower being washed out.

What he should do is look for a light with higher lumens as well as a higher beam rating. A light with +300 lumens and distance measured as 100 meters to 0.25 lux is going to be significantly brighter, with more throw and will be more resistant to being washed out by other light sources.

The issue with bike lights, among many, is that they often do not follow the FL-1 standard and play loose and fast with what "lux" means as well as overstate brightness and battery life. So it can be hard to determine when an upgrade is actually and upgrade and not just a different beam pattern or proprietary battery pack.

This direct link to a PDF is more helpful than my earlier link: https://www.streamlight.com/docs/def.../ansi-pres.pdf