The word “channel” is a catch-all. It covers several different kinds of companies that sit between the provider and you. They look similar from the outside. They are not the same.
A reseller buys technology from the provider and resells it to you. Their job is primarily transactional. They process the order, handle licensing, invoice you, and collect from the provider. CDW and SHI are large examples. Most resellers are much smaller.
A VAR (value-added reseller) is a reseller that also layers services on top. Implementation, configuration, integration, training. The “value add” is the services, not the resale itself. You are paying for both.
An MSP (managed services provider) runs technology on an ongoing basis. They often resell the underlying products you are using, then manage them for a monthly fee. The resale and the management are entangled. Leaving the MSP for a better price on the products usually means leaving the management too.
An agent sells on behalf of providers but does not take title to the product. You contract directly with the provider. The agent gets paid commission. Telecom and SaaS often use this model.
Each of these has a legitimate role in some scenarios. A buyer with no internal IT capability genuinely needs hand-holding. A complex implementation genuinely needs a VAR. An organization that wants to outsource IT operations genuinely needs an MSP. The problem is not that these roles exist. The problem is that you are routed through them by default, whether you need them or not, and you pay for the role whether or not it is adding value in your specific situation.
The category label (reseller, VAR, MSP, agent) tells you how the company makes money. It does not tell you how much of what you are paying is going to them, how those payments are structured, or whether any of that structure is aligned with getting you the best deal. Those are separate questions, and the system is set up so you rarely get to ask them.