The Dash 7 was initially conceived and marketed as a short-runway city centre airport STOL aircraft, high business pax fares so the costs of 4 engines was secondary. De Havilland had found that some of the predecessor 19-seat Twin Otter were starting to be used on such operations, so went for a 50-seat proper airliner. That market never really worked out for them, and of about 100 built some went to regular short haul runs at normal airports, which was wasteful, and some to bush/rough strip operators, which really didn't justify a new, expensive aircraft. The good old PT6 engine was also showing its age (I think it was the last new type to use it).
So they reduced the engines from 4 to 2, with the new PW100, reduced the fuselage length to a 37-seater to suit, and that was the initial Dash 8. They sold quite a few, but it took a while to bring together the twin engines (once P&W came up with a more powerful one) and the 50-seater capacity, which became the definitive type of the era.
The current larger still Dash 8-Q400 is a substantial rework all round, and really a different type.
not long afterwards the Il-114 emerged, which seems to be an ATP with a dose of Soviet ruggedness applied. Later '114s even had the same engines.
The IL-114 scarcely entered production, only a handful were built and hardly any of those used.
There were two which ostensibly ran with Vyborg Airlines in the 2000s. Apparently their only fleet members. I'm a regular into St Petersburg, and from my first visit in 2003, to about 2010 when they vanished, they both sat there side-by-side in the same position on the airfield alongside the north runway, with the props taken off. I presume they never moved in that time.