No P&R doesn't seem to damage the NRL.
Now personally I'd prefer P&R. I think it's the "natural" position for British sport. But only if the league can support it. P&R causes huge damage to both the club's relegated and those under threat of it.
Only football can currently properly support P&R because they have so many clubs and a strong, robust, fully professional 2nd division.
My view is that I agree with Jim/Gutters in that we should have licensing but a much stronger, more in depth, longer term version that has the teeth and the balls to kick a club out if necessary.
It should be a bare minimum of a 5 year licence but with in-depth targets across the whole range of a club including on-field performance. That should also apply to the Championship clubs as the aim should be to get a stronger Championship so that the gap between the 2 leagues isn't so great.
Then there should be a long term strategic plan to grow the SL to around 16 teams and the Championship to where at least half the league are full time. Then, at that point, P&R might be viable in some form.
Until then I just think it makes the bottom half clubs in SL unstable whilst the top half who don't realistically have to worry about relegation able to plan long term.