The number of treatment units (subjects or groups of subjects) assigned to control and treatment groups, affects an RCT's reliability. If the effect of the treatment is small, the number of treatment units in either group may be insufficient for rejecting the null hypothesis in the respective statistical test . The failure to reject the null hypothesis would imply that the treatment shows no statistically significant effect on the treated in a given test . But as the sample size increases, the same RCT may be able to demonstrate a significant effect of the treatment, even if this effect is small. 
Eventually Notes of Clarification (footnotes) to articles 29 and 30 were added in 2002 and 2004 respectively, predominantly under pressure from the US (CMAJ 2003, Blackmer 2005). The 2002 clarification to Article 29 was in response to many concerns about WMA's apparent position on placebos. As WMA states in the note, there appeared to be 'diverse interpretations and possibly confusion'. It then outlined circumstances in which a placebo might be 'ethically acceptable', namely 'compelling… methodological reasons', or 'minor conditions' where the 'risk of serious or irreversible harm' was considered low. Effectively this shifted the WMA position to what has been considered a 'middle ground'.   Given the previous lack of consensus, this merely shifted the ground of debate,  which now extended to the use of the 'or' connector. For this reason the footnote indicates that the wording must be interpreted in the light of all the other principles of the Declaration.