Yes that is true, but most of the time this happens in places where only a few pedestrians are likely to use it. I can count on one hand the amount of times in the last few years that I have needed to walk on a bike path as a pedestrian while working in Amsterdam and visiting many other cities and towns.
It happens I agree, but as far as I can tell there are few places in the Netherlands where more than the occasional pedestrian need to walk on the bike path for more than a few meters.
This depends on where you live of course, here in the Netherlands most big/well trafficked train stations have one or more secured bike parking.
The NS (Dutch National Railway) sells a secured bike storage subscription starting from 75 euros a year. And you can do it cheaper if you use your bike frequently because at some stations the first 24 hours are free.
And if you have a cheap bike that you use just for your commute you can also just put it in the free bike storage and only move it secured if you know you will be gone for >2 weeks or whatever the limit for free storage is.
It happens I agree, but as far as I can tell there are few places in the Netherlands where more than the occasional pedestrian need to walk on the bike path for more than a few meters.