This article (Michalski J et al. Ancient hydrothermal seafloor deposits in Eridania basin on Mars. Nat. commun. 8, 15978 doi: 10.1038/ncomms15978 (2017). shows that hydrothermal vents were on Mars too, about 3.8 billion years ago.
Ancient deep-water hydrothermal deposits in Eridania basin represent a new category of astrobiological target on Mars. To date, the search for habitable environments on Mars has been focused on exploration of ephemeral playa and shallow lacustrine settings. The Eridania deposits represent an ancient environment rich in chemical nutrients and energy sources. Such a deep-water environment would have been protected from harsh surface conditions and ideally suited for preservation of organic matter under reducing conditions. In fact, the earliest evidence of life on Earth seemingly corresponds to seafloor deposits of similar origin and age, although the terrestrial counterparts are metamorphosed and metasomatised. Eridania seafloor deposits are not only of interest for Mars exploration, they represent a window into early Earth.
Jezero crater was selected as the landing site for the Mars 2020 rover, mostly because it was also a deep lake about 3.8 billion years ago where lots of sediment was deposited. Although that sediment is ¨extremely good at preserving biosignatures", there were probably no rich energy sources favourable for the creation of life.
So, why not search for past life on Mars where the best chances for creation of life were ?