The Robin is made of timber with fabric stretched over it.
It's true that the TB9/TB10 are a poor choice for a flying school but that is true for nearly all planes.
Only the Cessnas and Pipers are OK for continual banging onto the runway - not because they are particularly solid but because everybody can fix them, and if you have a fleet of them you can buy parts direct from the USA.
The European new-certified-plane market has largely collapsed over the past 10-15 years. The prices reached the region of £120-150k (for a basic C172-type spamcan) in the early 2000s and almost nobody was interested. Cessna and Piper sales are miniscule now. Diamond and to a lesser degree Cirrus are making new ground. Very few new TB9s and TB10s were sold over the past 10 years and most TB10s on the market are 20+ years old.
Italy is the only country that had bought a large batch of Tampico's (Aeroclub d'Italia)15 years ago.
Not true - loads were sold to flying schools in the 1980s.
But none of the above is relevant to whether a used plane is any good or not.
I remember looking at a 1985 TB10 a few years ago; it was about £80k. I reckon the same plane today would go for about £40k. Plus the substantial maintenance which you will get on any 20+ year old airframe.
The problem is that the pilot forums are full of armchair pilots who have never owned or even flown in a TB and they just regurgitate the same old stories.