You can say that. You can also say a PhD is like a training qualification for the purposes of doing further independent research. To a first approximation these are probably the same. Thing is, between countries, universities, subjects, there are many differences in the academic culture that qualify what is reasonable to expect from a student in the training process and how a new idea might manifest itself.
My impression in Math was that there was quite a wide variation in the standard of thesis that would be accepted for the PhD qualification. I think there has been a policy for universities to be producing more PhD students that subsequently go and work in the wider economy. That means the university will ultimately set lower standards if the thesis is not to be the basis for an academic career.
The original PhD qualification was a German one I think, with the intention on training individuals for research. German PhDs to this day are frequently completed by people in their early 30s. US PhDs also structurally seem to be set up to take about 5 years.
In the UK, Oxford and Cambridge's notion of a degree was a 2 stage 3 year taught study process (there must have been plenty of room for various elements of self study too), awarding BAs after 3 years and MAs after 3 more that I think were about developing character too. People could drop out after 3 years but I don't think that was the intention when you started. After this, if you were impressive enough you could just start and become part of some academic institution I suppose. On an historical digression, now that the BA is the standard copied University qualification, Oxford and Cambridge retain and practice the right to award MAs (Oxon/Cantab) to BA students 3 years after graduation, without requiring further study (although being sent to prison or getting divorced used to disqualify you).
In summary, my impression is the "new idea" rule of thumb is slightly less applicable than in the past but as with primary and secondary school education standards, things change expediently.
Edit: experimentalists would be looking for results in any case:
