1) Lobbyists costs a lot of money. The amount Facebook spent on WhatsApp is equivalent to fifty times the annual lobbying revenues of the top 10 DC lobbying firms combined.
2) Lobbying money goes to politicians pockets. American politicians are some of the most thoroughly scrutinized on the planet. Lobbying money doesn't go under the table to some politician. It usually doesn't even go to campaign contributions. The major source of campaign contributions is rich peolple making personal donations, not lobbyists. Lobbying money goes towards advocacy. For example, a lobbyist might commission a survey to show a politician that a particular position, advantageous to a client, is politically popular. They may also propose draft legislation, connect politicians with experts, etc. What Google is doing is a good example of the bread and butter of lobbying: simply helping politicians understand the prevailing point of view of an industry.
3) Lobbying is the same as corruption. The vast majority of lobbying is about helping politicians find votes. Its about showing how what's good for an industry is good for constituents. The message is overwhelmingly not "if you vote for this, there is money in it for you" but "voting for this will save 100 jobs in your district."
Do lobbyists help corporations exercise substantial political power? Yes. But most of the american labor force works for large corporations. Their livelihoods and that of their kids depend on these corporations. Their healthcare and retirement depend on them. Corporations don't need to corrupt the political system to wield power.