Simenon is said to have described his stories as sketches, somewhat like preliminary drawings by an artist. This is not to say that the Maigret mysteries are unfinished, but they are perhaps lacking in decorative elements. This particular story - Maigret and the Man on the Boulevard - has elements, particularly the rather abrupt ending, that make it seem even less polished. However, the thesis is intriguing and this is classic Maigret with all of his daily routines and his personal foibles.
Maigret and the Man on the Boulevard reminds me of an early Sherlock Holmes mystery, The Man with the Twisted Lip, a tale of an apparently successful businessman, Mr. Neville St. Clair, that secretly poses as a beggar as he (unbeknownst to his family) has lost his job. Due to unfortunate circumstances the beggar is accused of murdering St. Clair (himself, that is), but refuses to reveal his true identify and thereby shame his family.
In Maigret's case, however, the secret identity of Louis Thouret only becomes known as Maigret begins investigating Thouret's actual murder.
Thouret's routine, that of spending his days sitting on a bench, provided no explanation for his substantial income. Maigret slowly peels back each layer of this puzzle, revealing a double life, duplicity, blackmail, theft, and murder. The introduction of the culprit, a stranger, a new character, in the final chapter is disconcerting, even though such events do occur in actual investigations. The astute reader, undoubtedly, would have considered this possibility or something similar as other leads proved untenable.
Maigret and the Man on the Boulevard was published in France in 1953, but was not available in English until 1975.