From talking to a few ex-googlers, a lot of issues come from heavy incentives (and upwards momentum in employment level/compensation) tied to shipping a product

From talking to a few ex-googlers, a lot of issues come from heavy incentives (and upwards momentum in employment level/compensation) tied to shipping a product/tool, while very little is tied to the maintenance/improvement of something existing. When combined with the ease of lateral movement (jumping from one team to another) means that a product gets shipped, then a lot of the team members jump onto the next shiny thing while that product now gets stagnant/buggy since it now has a vastly reduced team.