There are plenty of use cases where an established CSS framework is a good choice. For PoCs, internal tools or dashboards, or just short lived projects, you can get very far by utilising a framework.
But if you're building a product, or UX / design is important to your project's success, then I completely agree with the author. You will quickly run up against the boundaries of what the framework provides and start fighting it. The methods the framework uses for extensibility won't be adequate and will hinder your attempts to customise it in the way you want to. Starting with custom CSS means you build things the way that makes sense to you and your team, and avoids a costly refactor later when you decide to ditch the framework.
That does mean that your team will end up designing their own framework! Developers with enough skill and experience to do that well are not always easy to find.
I disagree with the criticism of SASS, but with all the new features landing in modern CSS, it's not nearly as useful as it was even 2 years ago.
But if you're building a product, or UX / design is important to your project's success, then I completely agree with the author. You will quickly run up against the boundaries of what the framework provides and start fighting it. The methods the framework uses for extensibility won't be adequate and will hinder your attempts to customise it in the way you want to. Starting with custom CSS means you build things the way that makes sense to you and your team, and avoids a costly refactor later when you decide to ditch the framework.
That does mean that your team will end up designing their own framework! Developers with enough skill and experience to do that well are not always easy to find.
I disagree with the criticism of SASS, but with all the new features landing in modern CSS, it's not nearly as useful as it was even 2 years ago.