Because weapons from Year 1 do not belong in the Year 2 meta. If weapons are never left behind then in year 10 we will have 3636282828636278292836367829299273638271772637495050574763663738392927636637349505955774737728929290172636647458595050583772616265152673839390509575747476366266155254664748495060688685746366265255155474748660070899476362651551442627383940508575363653562661617838404594646478393930273662727839998646366366281910284746366255151555568895966070707969686868685855775747476447646464366366363625551442263398495060606958747376266262653546748494040595863636366272949506070700794884737766152536374748489506594873763662625525353636474775858858585857477474746464664747478449229827364636366367484859959400404093838727272726626362625251551551563488590000958487636625141411112335637839569969584736365252553658596070708079584737636251515348856696994847736363662263633552525255363664747485859696983773615515638484949894040987762671716637475744506799684772626161466747558585996970979696858477474646464647646466251551515241431125738849606079688474763638292002928817266474858595940038377262652525444246264858869606604847376363663638489966006069484736363535525272929048477784940304747477303092726263667484848498847747477474775859505058376367389303047474848949404948747575747478930303082737474758956070707988776161114141452636477585859950505857477366352552525256383849940409487366436363773839020101763689099397477474839930226267384800974748399376506096857464663662614136374940473939weapons to choose from. Personally I think the arbitrary year line is a great place to mark weapons to be left behind.