In an RDBMS a schema change is both an application tier change and database tier data definition change and depending on what you want to optimize for that can

In an RDBMS a schema change is both an application tier change and database tier data definition change and depending on what you want to optimize for that can be a material difference in terms of agility. Anything can be described as "quite easily" but in a fundamental sense if a change requires you to reason and initiate at two layers and that change often requires downtime, you have a major impediment on your hands. You might also call slowing down a feature. I think it's a bit like fiat vs Crypto, there's a religious ferver aspect that drives some people to declare a position on this and a set of tradeoffs aspect.