In my experience the difference between good consultancies and average product companies is not very big. On average I've seen consultancies being able to attract more technically curious and product-minded engineers. The exception are the product companies that are somehow special in the market (e.g. can offer a significantly better pay, or do something very interesting in terms of scale or technologies).
The dynamic you describe tends to get stronger, when consultancies grow. The voices & competence of the technical people becomes less important when it comes to the business and efficiencies in utilization and the company brand start to matter more. The consultancy I worked at was not an incumbent, but an underdog competing with the big players, so the actual execution mattered more, when trying to win bigger customers. Even in consultancies, there are operational effiencies you get from having competent people. Mainly from having less middle management & account managers.
However, there things are useful for the consultancy's business only to a limited extend. You only need to be slightly better than the average consultancy and you're OK. So there is a point, when you either need to be great at sales or thought-leadering, or a consultancy can no longer increase your salary or provide your with work you find interesting.
Interesting on that first point, that's not what i would have expected. So what are you seeing from these product-minded engineers that leads them to choose a consultancy over a product company?
For "underdog" consultancies, i've always felt that they win by
1) sending their A team where an incumbent would be sending in their C team. That would make sense, as the incumbent's A team is on a more important client, whereas this small client "is" the underdog's important client.
2) carving out niches and specialties. So you serve less clients and projects, but also build up a reputation. You kind of become an incumbent of sorts, just for that niche.
Both 1 & 2 are valid strategies for underdog consultancies. Consultancies that are very good at #2 may also have better ability to keep people, who are exceptionally good at some specific tech or domain, because they usually have higher rates and peers that are good at the same thing.
As for product-minded engineers, there is often more freedom at a smaller a consultancy than in (many) product companies. You can switch projects every 3-18 months, select a new technology you want to learn, have big ownership on the helping the customer building the product, etc. To some people this is ofc a downside and a lot depends on the kind of client/project you're working in. Much of this also is lost, when the consultancy starts taking on bigger projects with bigger clients that already have much of these things set in stone.
The dynamic you describe tends to get stronger, when consultancies grow. The voices & competence of the technical people becomes less important when it comes to the business and efficiencies in utilization and the company brand start to matter more. The consultancy I worked at was not an incumbent, but an underdog competing with the big players, so the actual execution mattered more, when trying to win bigger customers. Even in consultancies, there are operational effiencies you get from having competent people. Mainly from having less middle management & account managers.
However, there things are useful for the consultancy's business only to a limited extend. You only need to be slightly better than the average consultancy and you're OK. So there is a point, when you either need to be great at sales or thought-leadering, or a consultancy can no longer increase your salary or provide your with work you find interesting.