Traditional systems generally have additional costs with upgrades, and to assure the customisation in the systems that clients already have. This might be challenging, depending on the complexity of the customisation.
Furthermore, traditional systems use a customised code base. This means that as a business’s requirements inevitably change, the system will need to be re-coded, increasing the effort to adjust to business, and at the same time bringing higher time to market, which might impact the client’s business. Additionally, the clients will inherit a higher tech debt, which is hard to sustain in the long term.