Bret Devereaux

... These changes included the graduate replacement of maniples with cohorts as the key tactical unit of the legions, as well as a shift from conscripts to volunteers (beginning with Scipio Aemilianus in 149) and the eventual recruitment of property-less Romans. ...

... These changes, motivated by a mix of political and military concerns, have often been associated with the career of Gaius Marius (cos. 107, 104-100, 86), though his career represents only one stage in a larger process. ...

... The impact of these changes, occurring over decades, was to steadily detach the interests of Roman armies and generals from those of the Senate, contributing to the chaos of the first century BCE and the eventual collapse of the Republic." (fin)

As it stands, the article in question is going to deceive on the most fundamental point: it is going to convince students that there were a set of key reforms, and Marius did them at a specific point in history. Which is wrong! Gradual process, occurring over decades...

...in which Marius is only one actor and not necessarily the decisive one, even though he is given a lot of credit by our literary sources.

The most complete pushback on this is probably Cadiou's *L'armée imaginaire* (2018) - review here: https://bmcr.brynmawr.edu/2021/2021.06.02/ … - but even Keppie, *The Making of the Roman Army* (1984) - note that year! - presents the 'Marian reforms' as a gradual process...

...comments that giving Marius the lion's share of the credit for this shift is (and now I use a quote correctly), "As will become apparently, this is a considerable over-estimate of the scope - and results - of his work" (Keppie, op. cit. 57).

Anyway, don't use the World History Encyclopedia, it isn't very reliable. Wikipedia is often very flawed, but generally a better starting point because it will point you towards actual professional scholarship in the bibliography and notes.