Plenty of people grow vegetables in containers, so as long as you plant them in large enough containers, you CAN grow them to maturity.
Most of the time, reason against starting inside is that they either have brittle thick roots or fine roots that break easily or tend to grow incredibly long tap root eary on in growth. Even if you manage not to break the roots, you can't plant the tap roots and side roots to the depth and width they were intended to grow, ending up with scrunched up roots in the planting hole.
Also, most of the vegs that are recommended against starting inside need lots and lots of sun -- FULL sun. They may also benefit from the huge fluctuation in temperature between day in direct sunlight and night, including the high temp. These are near impossible to provide inside.
So you end up with wimpy starts. Then having their roots broken or disturbed sets them back and sometimes they don't recover, or by the time they do recover, seeds that were directly sown in the ground have grown as big or have overtaken them.
So what's the point of all that effort?
Well, sometimes you want to grow things that require longer time to grow to maturity than you have growing days for. Then you HAVE to start the inside and give them extra-heroic care to give them a head start. But fast growing beans, cukes, and summer squash don't seem worth the effort.
Oh, some people get the jump on summer squash and zukes because they want to get them to harvest size before the SVB'S and squash bugs arrive and destroy them all.