To say it only hurts legal owners of crossbows as 'criminals' would still have them doesn't make sense IMO...
1987 Hungerford massacre... legally owned weapons
1996 Dunblane massacre... legally owned weapons
2010 Cumbria massacre... legally owned weapons
2012 Horden shooting... legally owned weapons
2021 Plymouth shooting... legally owned weapons
add to that the many documented stabbings, bombings & vehicular killings.
Yes, criminals will have a source for weapons if they want one but personally I'm not keen on any knee jerk reactions for legislation, as much as I appreciate 'militaria' I can also appreciate the hoops a UK resident needs to jump through to obtain a weapon legally, crossbows are cool, longbows etc are cool too but I'd rather see a license requirement for them than a complete ban.