This is a form of golden handcuffs to keep you with the employer. If you leave before the employer match money is vested, you don’t get it. 5 year “cliff vesting,” where it is all vested at once after 5 years with the company is common, but so is immediate vesting and there are plenty of options in between.
Since you’re leaving the employer, you could easily just roll the money over into an IRA and withdraw it if you so chose. So you’re really guided by the IRA rules outlined in Publication 590b.
Lots of people just starting out saving for retirement allow their Roth IRA to double as an emergency fund, investing it more conservatively than they otherwise would if they had a separate emergency fund.
If you just raid your retirement accounts (or your home equity) every time you want to buy something, you may arrive at your 60s without much net worth at all. You’ll then be working because you have to (if you’re lucky) or eating Alpo (if you’re not lucky.)
There is a concept in financial planning known as “consumption smoothing.” This is the idea that you borrow money when you’re young, gradually pay those loans back while also saving money as you get older, and then spending your savings in retirement.