I don't think anybody carries a valve spring compressor in their toolbox. Plus you'd run the risk of dropping the valve unless you was really careful and good luck getting the keepers back in on the side of the road without a way to hold the valve up. Even then who has the parts with them to make this a 1/2 hour job? Cars are just as hard/easy to fix now as back then. Fuel injection is arguably easier to troubleshoot then a carb given the computers help.