I believe Mr. Waller is correct. Generally "small" would be based on the work envelop - which of course is relative. I have quite a nice 11" swing lathe, only 24" between centers. In many, many environments - that would be considered pretty small. The base machine tips the weight scale at 2700 lbs. That does not make it "big". The work envelop is still only 11x24. It is a particular category of machine, built at a time when people, companies, businesses would pay for a high quality little lathe.
As others have pointed out, plenty of very nice, small work envelop lathes have been made over the years. The one I am referring to was made by Smart & Brown, but there are plenty of others.