One other thing that happened in the dot-com era, which is also happening today, is that many new companies would spend fresh funds raised from VCs and even from IPOs to buy products and services from each other, spending money aggressively to deliver such products and services, and generating revenue growth that would look impressive in the short run... but ultimately would prove unsustainable. Such growth can last only as long as there is an ongoing supply of fresh capital!
At the extreme, some companies in the dot-com era engaged in dubious "round-trip revenues" behavior, e.g., agreeing to buy a certain dollar amount of another company's products/services only if the other company agreed to do the same, with neither company actually needing to do so for ordinary business purposes. I don't know if this is happening today too, nor to what extent.
Theoretically, who cares. If you can convince people to buy your product - even if only to scratch each other's backs - that's better than all the other people who can't / don't have the network.
At the extreme, some companies in the dot-com era engaged in dubious "round-trip revenues" behavior, e.g., agreeing to buy a certain dollar amount of another company's products/services only if the other company agreed to do the same, with neither company actually needing to do so for ordinary business purposes. I don't know if this is happening today too, nor to what extent.