The speculative activity equates prices and, therefore, sends the right signals to market operators as to how and where to most efficiently allocate their resources. But this is the passive speculator. He corners the market by the dubious virtue of his reputation and size. Middlemen are a different story because most of them belong to the active subcategory. Leaving ethical questions aside, this is a highly wasteful process.
Speculators normally work within closely monitored, full disclosure, transparent markets.
Middlemen thrive of disinformation, misinformation and lack of information. The same process will likely apply to middlemen of goods and services. The short and the long of it is that competition enhances and increases efficiency and that, therefore, anything that restricts competition, weakens and lessens efficiency. The world goes in circles of increasing and decreasing free marketry. The globe was a more open, competitive and, in certain respects, efficient place at the beginning of the 20th century than it is now.