Given that now a new kind of space race between private entities seems to be on, and the trend toward micro satellites is continuing, we are going to end up with lots and lots more objects in LEO (and AFAICT these satellites are indeed in LEO), which just increases the potential for cascading failure as Kessler predicted. Or were you assuming that none of these satellites would malfunction?
88 small commanded satellites in a high drag LEO circular orbit contribute to Kessler syndrome in the same way that your production of CO2 contributes to global climate change. Your attitude is just as anti-science as that of people who think Jesus rode a dinosaur.
LEO isn't the problem. Anything in the orbit these are in has a lifetime of a few years at most unless they have active propulsion (i.e. not debris or microsatellites).
The problem with space debris is mostly higher orbits where it will remain in orbit indefinitely. In LEO, the atmosphere does a good job of "cleaning up" debris and inactive satellites.
This launch was to 500km, and the Doves are around 150kg/m^2 (4.5kg / 0.03m^2). This puts their lifetime at around 5 years according to that linked plot.
For reference, Planet's earlier launches were to the ISS (400km) and lasted less than a year, which your plot agrees with.
