I respectfully disagree. At a company like Twitter, the so-called "insiders" have been able to take plenty of money off the table. And in fact, I'm not totally sure what share (if any) of the offering is from shares held by officers and investors. Have you seen the data?
Moreover, there is liquidity on the secondary market for Twitter like there was for FB, etc.
I think the primary object here is to raise capital and lubricate M&A activity. And most companies have no secondary market, so an IPO really helps unlock value for the rank-and-file who aren't part of the Series-XYZ rounds. There are a lot of engineers and middle managers there who will be able to buy homes and lots of other nice toys not to mention diversify their net worth a little.
RSU grants given to employees (including large grants given to new executives and key employees) are typically illiquid until 6 months following an IPO. The company has to IPO to make good on the compensation given to hire and retain their employees. If they never go public, employee compensation is worthless, and they cannot hire nor retain the best people.
Most often pre-IPO companies grant options not RSUs. And the lock-up period is a post IPO lockup designed to stabilize the price of a newly offered security while it finds its market.
The existence of a lock up period does not inhibit pre-ipo trading on the secondary market, though to be clear there is no truly liquid "secondary market" for most companies.
Moreover, there is liquidity on the secondary market for Twitter like there was for FB, etc.
I think the primary object here is to raise capital and lubricate M&A activity. And most companies have no secondary market, so an IPO really helps unlock value for the rank-and-file who aren't part of the Series-XYZ rounds. There are a lot of engineers and middle managers there who will be able to buy homes and lots of other nice toys not to mention diversify their net worth a little.