Turbo Pascal, Borland Pascal and Delphi all suffered from the curse of units. Units were great, way superior to C/C++ compilation allowing fast compiles and efficient stripping of unused code. But they were version incompatible. If you lacked the source code for a compiled unit, you could never move to a later version with it.
But give it its due, the stuff you could do with Delphi for example COM made it probably the only Win 32 compatible language to compete with C++. It was the Betamax to the VHS of VB...
Units between versions were mostly not a problem due to the culture.
Virtually all third party commercial libraries had source available, which had a raft of benefits (even if you often needed to pay more for the library to get the source.)
Meanwhile for other languages, libraries were often sold without any source, and you were royally screwed if you had a problem later.
But give it its due, the stuff you could do with Delphi for example COM made it probably the only Win 32 compatible language to compete with C++. It was the Betamax to the VHS of VB...