A 'tech company' is that is internally built of software, so it is (theoretically) as easy to evolve as software - which is not that easy, except compared with anything else. So, amazon, stripe, airbnb, uber, reddit, github etc. Perhaps a bit like when companies started to be built around the new-fangled telephone instead of telegrams and dictated letters. More responsive and free-form.

This does not guarantee a strong competitive opportunity, nor strong execution - but it makes it possible for the benefits of IT to be realized.

Actually, there are several legitimate definitions of 'tech company', this is just a relevant one today that is significant long-term.