1. Whether a professional is or isn't a scientist shouldn't concern the question of professionalism, since expertise is not the same as science (especially not if the term science is equated with something like physics). An airline pilot is not a scientist, but one hopes that he or she will uphold the professional code of ethics & make as few technical errors as humanly possible.
2. Norms & techniques may be analytically separable, but in practice these are often inseparable. Ideally, the professional code of ethics (= norms) should include: (1) make as few technical errors as humanly possible; (2) strive to create the working environment in which there is no fear of malicious reprisal against reporting one's own & others' errors, exposing institutional problems, attempting to address political questions that shape institutions, professions, & society in general, etc.; (3) become capable of distinguishing legitimate authority (= authority based upon superior knowledge, be it theoretical or experiential, & mastery of craft) from illegitimate one (= the Boss's demand for deference just because he or she is the Boss) & obeying the former while scorning the latter; and so on. Good norms of conduct should lead to fewer technical errors, whereas bad norms would result in more technical errors than otherwise. Therefore, appropriate socialization is indeed important -- as important as technical and/or theoretical expertise. The question is into what norms professionals should be socialized: a "conspiracy of silence" (= protection of one's peers, superiors, and/or subordinates to the detriment of clients and/or the public) or norms of good practice that lead to fewer errors & are subject to public accountability?
3. Technical errors are not homogenous, and not all of them are individual responsibilities. Overwork, for instance, leads to more technical errors than otherwise, & sometimes such errors are deadly (= deadly to clients, professionals, and/or third parties). Primary responsibility for technical errors that originate from overwork should be placed upon the ensemble of social relations that creates overwork, not upon erring overworked individuals; otherwise, the cause of such errors cannot be eradicated. Technical errors may be innocently made. Technical errors may be made by novices who should be under proper supervision of experienced practitioners but are not (due to the negligence of their superiors or institutional problems such as staff shortage or both). In such cases, it is proper that errors of the novices should be remembered but forgiven. Technical errors that should be neither forgiven nor forgotten are those that result from moral errors (e.g., malice, criminal negligence, greed, & other breaches of the code of ethics leading to technical errors).
3. Deference & degradation are not the same thing. It is sometimes though not always proper for a professional to defer to the judgments of (A) the more experienced, be they clients, peers, superiors, or inferiors; and/or (B) the public. Degradation is by definition evil, but it is not inherent in deference. Rather, degradation stems from bad working conditions; conflation of legitimate & illegitimate authority; competition for merit raises, promotion, etc.; absence of public recognition of work; and so on.
In my opinion, under capitalism, professionalism is a poor substitute for -- and often an obstacle in the path toward -- working-class solidarity. However, it doesn't have to be this way. As Wojtek argues: "Successful social democracies have been build on professions-working class alliances." So will be socialism, if we ever get around to building one, I think.