I think it's possible to see both sides of this.
Some integrators prefer to be end-to-end experts on all aspects of their products. This gives them (at least in their perception) more granular understanding of the products they support, a greater ability to craft custom solutions, and the ability to solve/fix any issues that arise over time. These companies tend to have very technical-oriented leadership (in my experience), and so this culture/concept pervades through the company.
Other companies see their strength as being able to amass a large number of contacts/relationships with experts in various technologies or solutions, so that when a customer has a particular problem or need they can bring the proper individual experts/products together to create a solution. These companies tend to have more sales/marketing or "general business" oriented leadership (in my experience), and the spirit of the company leans more towards being a kind of "trusted advisor" than technical expert.
The downside on the tech-heavy concept is that it tends to be more time-consuming for everyone in the company to keep up with what is the latest/best RAID controller (for example), and what are the optimal BIOS settings and so forth. Though many of the kinds of people attracted to these companies see these things as half fun/half work, so it's not terrible. You'll also likely find the employees at companies like these can command a higher salary, so their payroll costs may be higher than average.
The downside to the "trusted advisor" kinds of companies is that they may miss major trends, or not realize the full capabilities/limits of certain products, though this is potentially offset by maintaining the right relationships. A customer might ask for a solution or configuration that is technically possible, but this company doesn't realize it and either says no to the job, or has to spend too much time researching the answer instead of just configuring and quoting a system.
Overall, many customers may not care which company type they deal with, as long as they get a reliable solution for the money. However, there are surely customers who prefer each type of solution provider. Some customers will want their contact to be an expert on everything and able to fix any issue or answer any question, and other customers may have more confidence "knowing the guy that knows the guy", where they look at their integrator as being able to solve MOST problems, and get expert help for other issues.
In the example above, if the engineer is really "experienced", I think you could expect them to have other domain expertise in place of knowing intimate details of server configurations. If that engineer really has knowledge that is more "a mile wide and an inch deep", then they are not (IMO) "experienced" as much as they are just familiar with things and been around a while.