a significant portion of cost was subsidized by the Italian government
Well' that's not actually true. The State in Italy (and in other European countries like France, BTW) owns some companies, and many more it used to own. Many of these companies were formally run as any other company, just the Treasury was among the shareholders (or the only shareholder in some cases).
In some periods (when looking for money), the Government was even pushing for dividends, but it's true that usually the State either asked the companies just to have even balances, or pushed significant amounts of money when it was felt it was in the national interest: for instance post-war reconstruction (when the money actually came partially from US) or for steel production plants in the Sixties. Italy low steel production was a historical reason of weakness for Italy. Now everithing is changing, but Italy is still the second producer of steel in Europe (or third, if you consider Russia), so the State actions can't be deemed unsuccessful
Regarding Alfa Romeo, it had even or nearly even balances for a long period. You can find the yearly balances from 1954 to 1985 here:
Bilanci Alfa Romeo | Byterfly They are in Italian, but you get the idea.
The truth is that Alfa never recovered from two events: the '73 oil crisis and the Alfasud. The latter was a truly political decision (subsidized, but Alfa had to sign funding contracts).
When the CEO Luraghi asked for money to enlarge the Arese plant to build more Alfettas, that were in high demand, money was refused and instead offered to build part of the Alfettas in Sud plants. He refused, and resigned. This was one of the events that sealed the fate for Alfa.
So, it's true that design at Alfa was more dominated by engineers and less by beancounters, but they manged also to even the balances until the Seventies crises. Whhere money was needed, in the development of new cars, it was often not available. If one realizes the chronical lack of funds for development, and that the last car really designed from scratch was the Giulia (or the Giuietta if one wants to be picky), it looks like a miracle. I think that the perspective should be partially changed: the Alfas weren't extraordinary cars because they were partially paid by Italian tax-payers, they were extraordinary cars in spite of scarce investments. I think ths achivement really needed a commitment from administrators, engineers and workers
Regarding the De Dion, there is a testimony from Giuseppe Busso, variously reported, according which the De Dion was the most expensive and technically best of the three rear suspensions studies proposed for the Alfetta. Probably, I would add, it required less development costs (as opposed to build cost) than a true IRS system, given the experience of Alfa engineers