Online marketplaces that connect disabled and elderly Australians with small businesses offering support services need to be part of the solution to cost blowouts in those sectors, the former small-business ombudsman has said.

Kate Carnell AO, who in March finished a five-year stint as Australian Small Business and Family Enterprise Ombudsman, has just joined the board of Mable, an Airtasker-like marketplace that allows Australians in need of aged care or disability support to find sole traders and small businesses offering such services in their neighbourhood.