>>Two at each step, the existing polymer and the single base or second polymer is incorporated in to the chain
No ribosome required?
https://en.wikipedia.org/wiki/Ribosome
“No ribosome required?”
No. Not at all.
The write-up you saw and excerpted is the sort of thing I’m talking about, but it has some errors.
The ribosome is a much more developed structure, it is RNA and protein and it is the molecule that translates DNA in to protein by catalyzing the protein bond reaction. The ribosomal RNA is the catalytic part of the ribosome, not the protein. That was discovered about 20 years ago.
The author of the excerpt you posted meant to use the term ribozymes which means literally and simply, catalytic RNA.
So yes, it is RNA alone.
Tom Cech won the Nobel Prize for thus discovery which took place in the 80’s.