Sometimes this system had undesired consequences with presidents that had no working parliamentary majority, such as Juan María Bordaberry in 1971 with 22.81%, or Luis Alberto Lacalle in 1989 with 22.57%.
Provinces have complete freedom to elect local and national representatives using the method of their choice; the system propagates down to the municipal level (except in the hypothetical case of autonomous cities).
The ley de lemas presents itself as a solution to the problem of fiat selection of candidates performed behind closed doors by party factions.
By allowing many candidates to run within the same party and leaving the decision to the citizenry, the system is supposed to end the practice of dark intra-party alliances and add transparency to the conflicts between internal factions.
It also avoids primary elections (which, in the case of Argentina, had never been practiced widely during the 20th century and typically enjoyed very low voter turnout).