I would argue that it depends quite a bit on the circumstances.
If the founder(s) or CTO hired a team of web developers to be full stack developers without actually figuring out whether they have the skills to do that or not, then the ones doing the hiring should be on the chopping block especially if they then took no action to properly train their employees and/or review their output.
It's a much more likely situation that whoever actually created the application without database indexes had no idea how to operate a database and were asked to do so anyway. That's not their fault in almost all cases.
