Serie A clubs did not own the stadiums but they also relied a lot on rich owners like Berlusconi, Moratti, Calisto Tanzi, Cranotti etc. Their model like the English one was based on buying good players and not really develop talent like the English. They were ,and still are, not adept at marketing their league and even negotiating for TV rights I believe was being done collectively with some lower division clubs. A lot of the clubs at one point were faced with the financial situation Chelsea and Liverpool faced i.e. being at the precipice of collapse or had to conduct fire sales like Leeds. Lazio went through it as well as Parma being linked to Tanzi and his business, Moratti threw so much money at Inter over the years buying so many players and hoping it would work out and was left with a bad structure and contracts that weighed on them once they stopped performing. Their fan culture is not as good as well, the English found ways to do away with the "undesirable" elements and corporatized with the prawn sandwiches and all while Italy still has some of that old style fan ,ultras etc.
The stadiums have not been mordenized as well and after Italia 90 I think they never really thought of long term development. Napoli's stadium is a case in point and the attendance of Serie A games is also not good at all, I read that it is one of the reasons Juve moved from the Delle Alpi to a smaller capacity one , if you look at the San Siro outside of the derby you see vast spaces. Calciopoli was however the final blow IMO in killing the league as it ceased to be a destination for any players in their prime, its funny watching players leaving England to play in Serie A after their done when Chelsea built of their late 90s squad out of the opposite movement with DiMatteo,Vialli,Zola,Guillit and other players like Ravanelli also joining the league after they were done.