Get share price down, for public companies. Still an issue today. Apple at $1000+ makes each share hard to buy for smaller investors.
Match a typical IPO share price, pre-IPO. Start-ups still like to IPO around $15-20 per share, plus or minus. This gives room for a “pop” and a share price still well under $100. If your private, pre-IPO share price is say $40, then a 2-for-1 forward split will get that down to $20, with the same economics for each shareholder and employee.
Apple and Tesla are both splitting their stock at present. This is to really drive some demand with smaller investors and allows them to have ownership over a great number of full stocks.