> Mature systems tend to have lower Evolution. Thus, there are more bugs being fixed than created. Ideally. But in practice, they must add features to sell mor

> Mature systems tend to have lower Evolution. Thus, there are more bugs being fixed than created. Ideally. But in practice, they must add features to sell more copies. And even if they have no evolution, OS's evolve that make the software worse over time (e.g. "modern" UIs, hardware vs software rendering, etc.). We see this in many products that were once best-of-class, e.g. Paint Shop Pro, ACID Pro, etc.