I think today, most often than not, the fault is between the keyboard and the chair. There is clear lack of domain knowledge. RDBMS's like PostgreSQL, Oracle, DB2, etc. can do much more than people expect them to do.
Relational databases are relatively easy for anyone to start working with, but optimizing and tuning queries requires fair amount of domain knowledge. You'd be surprised to learn how little denormalization big financial company databasees have. They have people who are experts that do only databases.
For I/O intensive work you may need transaction rows where data written together is stored together, but it's not denormalization, it's optimizing for I/O bottleneck.
Query planners can do most of the work, if the person crafting queries has understanding of how they work. Carefully grafted queries and tuning memory layout for tables correctly is usually the right way to fix performance problems.
Because, unlike most products which only require training to work with, true RDBMSs require knowledge of data and relational fundamentals and such is scarce today, because education has been replaced by sheer training.
How many database "experts" do you know today who have any background in logic and math, particularly those designing DBMSs?
I've watched them for almost 50 years and they've become worse and worse, not better.
Relational databases are relatively easy for anyone to start working with, but optimizing and tuning queries requires fair amount of domain knowledge. You'd be surprised to learn how little denormalization big financial company databasees have. They have people who are experts that do only databases.
For I/O intensive work you may need transaction rows where data written together is stored together, but it's not denormalization, it's optimizing for I/O bottleneck.
Query planners can do most of the work, if the person crafting queries has understanding of how they work. Carefully grafted queries and tuning memory layout for tables correctly is usually the right way to fix performance problems.