There should be no 'Watts' for anyone who hasn't actually used a powermeter in cycling.
It is very confusing to have an estimate for power on the activity page but also on individual segments for rides that were completed without a powermeter. The estimates are just wrong as there are so many influences that you cannot calculate for, biggest being head- or tailwind and whether it was a group ride with potentially lots of drafting.
I'm not only saying this because I'm comparing myself to other riders for activities or on segments but also comparing my own pre-powermeter rides to the ones with the powermeter.
Or at least clearly indicate that it's an estimate and not based on actual data.