This is a reason why when life pushed me away from product development into consulting/agency work, I hated it at first and eventually I learnt to appreciate the positive side of it.

Usually those kind of companies won't hire old employees, while at the same time will gladly pay for consulting knowledge to solve their problems.

Also while product companies tend to hire folks that the very last thing they worked on checks all bullet points on the HR job ad, agencies will gladly throw people at a problem regardless of the skills list, as long as the team learns to swimm fast enough.