Delaying profits is a perfectly valid strategy, but that implies intent. I guess however most of these modern startups are having no profits because they aren't managing to make them, and not as part of a bigger strategy.

Exactly. Delaying profits means having a knob in your cash allocation (usually sales) that you can turn down and become profitable. If you turn it down and still can't fund the company... you weren't delaying profits.

Pre-profit doesn't just refer to your cash-allocation-adjustment scenario. There's also the broader notion of what you focus on. A company may be pre-profit because they're not prioritizing profitability as a strategic objective early on. They may have no (current) way of turning a dial and becoming profitable, yet still be making the correct strategic decision to ignore profitability for the sake of e.g. growth or product development. Countless now-gigantic, now-profitable companies started as startups who were intentionally (and correctly) focusing on strategic objectives other than profitability.