That's not entirely true. Even ignoring the elements that were explicitly about formatting and have since been deprecated, the order and nesting of elements could have a profound effect.

For example, the entire model for how to do layout using CSS floats fundamentally depended on the order of elements in the source HTML document. It wasn't until much later that CSS finally added tools like flexbox and grid where you could explicitly reorder the content from multiple source elements in the rendered output using CSS alone.

Even today, certain effects such as column-based formatting for a table are much easier to specify in CSS if your HTML has additional elements such as <colgroup> included, yet there is little reason to include such elements in the markup except to support that kind of formatting.