Hi Rick, that's an interesting perspective, one which I have already taken some time to reflect on over the course of the last year. The reason I have given it some thought is because I came to 2 conclusions related to your point, 1 before the other:
1. I am not a good discretionary trader. I never have been, and so I've always looked to defining and using technical setups that I can stick to in order to remove the discretionary aspect of my trading.
2. I am also not a particularly good manual trader (at least in FX anyway, with equities I do ok probably because of the longer timeframes which I trade equities). The main reason is even with defined technical setups and a rigorous process (using trade rules, checklists, etc) I have discovered this year that I make way too many mistakes. Breaking trade rules is not my problem, it is all mistakes related to identifying defined setups, placing orders, etc. I already started to have this problem since last year when I started working heavily with spreadsheets - I just couldn't believe how often I made data entry errors that I had to find and de-bug later. I suspect that at the age of 50-something I have learnt I may be partially dyslexic (the preferred conclusion - the other being I am just stupid, lol).
As to your statement specifically, the view I have come to is its not a case of one being better than the other, its a case of different pro's and con's:
Being a good manual trader I think can be achieved either by being a good discretionary trader OR a good process-driven trader that doesn't make mistakes.
The pro for manual trading is that there is often some degree of latitude requiring discretionary decisions - hence needing to be a good dicretionary trader - the more rigorouse or black and white the trading rules, the better it is for a trader who is a good process-driven trader but perhaps who is not a good discretionary one. I suspect though that the more a setup definition or trade rules becomes rigorous with less latitude for discretion, the lower the average win per trade will be. The reason - the less black and white that trade rules are, the harder it is for a process-driven manual trader or an EA to mimic the results that can be achieved by a discretionary trader. Certainly the con for EA trading in this scenario is that it becomes hard and harder to write an EA that can replicate the less black and white aspects of a trading system, requiring the trader to becocme a better and better programmer.
The con for manual (discretionary) trading and the pro for EA trading is scalability - yes it may be difficult to replicate a less than black and white trading system with an EA because of the programming complexity, but there are degrees of complexity and so by sticking to simpler trading systems for which it is possible to write EA's more systems and more markets can be traded than a good discrretionary trader can ever trade manually.
Essentially I think it comes down to a question of margin (average profit/trade) versus scale (i.e. volume of trades) - a good discretionary trader can probably achieve a higher margin per trade than a good process driven manual trader or an EA, but the scale that can be achieved by trading with EA's can I think more than compensate for the lower margin - the classic economies of scale question.
This is why I think its not a one is better than the other question - its a question of which approach a trader prefers. Does a trader want to be the Ferrari of trading (or cherry picking, as you say, lower volume of trades but high margin) or a Toyota of trading (higher volume of trades but lower margin).
My conclusions about myself and my strengths/weaknesses favour the Toyota approach (I suspect if I were to try and build Ferrari's the wheels would fall off!) using EA's - because it caters to my strengths (research, statistics, product development testing and commercialisation - all part of my professional background), and avoids my weaknesses (discretionary trading decisions, manual processing) - hence why I am pursuing EA develpment and aim to trade totally by EA.