It is business.
A bookmaker prices every market with a margin built in, counts on that margin across a large pool of customers who pay it, and therefore reads the one customer who keeps taking prices better than the market as a running cost, which a lower stake limit removes far more cheaply than a change of price for everyone.
That is the whole mechanism, and it needs no grudge. The bookmaker does not have to decide that you are cheating; it only has to see that your bets cost more than the margin you pay. Stake limits, withdrawn offers and closed accounts are how that arithmetic reaches your screen.
Who gets limited?
Three profiles tend to run into restrictions. Value bettors take prices that are better than the bookmaker's own estimate. Arbitrage bettors set the price at one betting site against the price at another. Sharp bettors are the ones whose results show an edge over a long run. What the three share is a record that beats the margin, and a bookmaker that lives on the margin reads that record as a threat.
We think this is the single best reason the whole bet broker category exists. A soft bookmaker (one that earns from its margin and limits the customers who beat it) is telling you what it sells, and it is not a service for people who bet with an edge. We would not build a betting life on it.